Need help with the Wiring Regulations?

Yes. Regulation number(s): 411.3.3

Yes, as long as the division of final circuits between the RCDs is carefully considered so as to minimize the consequences of unwanted tripping. Separate RCD protection is not necessarily required for each circuit of an installation but, in order to minimize the likelihood and consequences of tripping, a single (‘front end’) RCD should not be used to protect all the circuits.

Regulation number(s):

Socket-outlets other than a SELV socket-outlet or a shaver supply unit are not permitted within 2.5 m horizontally from the boundary of zone 1.  In all other cases, only the general rules apply, in that equipment shall be of a design appropriate to the situation in which it is to be used or its mode of installation shall take account of the conditions likely to be encountered.

Manufacturer’s installation instructions shall be taken into account when selecting equipment.

Regulation number(s): 

• 134.1.1
• 512.2 
• 701.512.3

Yes. Meter tails concealed in a wall or partition at a depth of less than 50 mm from a surface must be protected in accordance with Regulation 522.6.202. Also, irrespective of the depth from a surface, meter tails concealed in a wall or partition having internal metallic parts (except nails and screws, etc.) are subject to the requirements of Regulation 522.6.203.

Regulation number(s):

• 522.6.202
• 522.6.203
• 522.6.204 

Yes. Where the generic term ‘RCD’ is used, it refers to most types of residual current device including RCBOs (Residual current-operated circuit-breakers with integral overcurrent protection), RCCBs (Residual current-operated circuit-breakers without integral overcurrent protection) and SRCDs (Socket-outlets incorporating a residual current device). For the purposes of the Regulations, it does not include PRCDs (Portable residual current devices).

There is no specific requirement in the Regulations for boiler pipework to be supplementary bonded. However, such bonding may be called for in the boiler manufacturer’s instructions, in which case BS 7671 requires those instructions to be taken into account (Regulation 510.3 refers). Any stated instruction for additional bonding that is considered to be unnecessary should be queried with the manufacturer concerned, and amended installation instructions requested.

Yes

Yes. The risk of penetration by a nail or screw is the same as for any other concealed cable. Also, if the wall or partition has internal metallic parts (except nails and screws, etc.), RCD protection in accordance with Regulation 522.6.203 is required irrespective of the depth of the cable from the surfaces.

Regulation number(s):

• 522.6.202
• 522.6.203

Yes, if the effective current carrying capacity of the cable is at least 12.5 A (20 A × 20/32), so as to effectively have the same ‘deemed to comply status’ as Regulation 433.1.204 gives to 30 A and 32 A ring final circuits.

Regulation number(s):

• 433.1.204

There is no specific requirement in BS 7671 but, if there is considered to be a significant risk of a lightning strike, the advice of a lightning protection specialist should be sought.

Whilst main protective bonding is required at the main intake position, it is good practice also to provide main protective bonding in each flat even though, in this case, the origin of each installation could be considered to be at the main intake position.

Regulation number(s): 

• 411.3.1.2

No.

No, but the device does need to be so placed and marked as to be readily identifiable and convenient for the intended use 

Regulation number(s):

• 537.3.2.4

Yes, provided that they are securely fixed to rigid parts of the units that are not demountable or otherwise liable to be disturbed in normal service. However, care must be taken to comply with all the relevant requirements of BS 7671, including accessibility for inspection, testing and maintenance, and provision of adequate protection against damage (by impact or water for example) for the accessories, equipment and associated wiring.

Regulation number(s): 

There are no particular requirements or limitations in BS 5839-6 concerning the use of RCDs with Grade D fire detection and alarm systems.

For Grade D systems, which comprise one or more mains-powered smoke alarms each with an integral standby power (such as typical domestic smoke alarm with battery), BS 5839-6 simply recommends that the mains supply to the smoke and/or heat alarms should take the form of either:

i) an independent circuit at the dwelling’s main distribution board, in which case no other electrical equipment should be connected to the circuit (other than a dedicated monitoring device installed to indicate failure of the mains supply to the smoke and/or heat alarms), or

ii) a separately electrically protected, regularly used local lighting circuit.

We recommend option ii) on the grounds that disconnection of the supply to the fire detection and alarm system will be more readily noticed. In our opinion ‘separately electrically protected’ does not preclude sharing an RCD with several other circuits where this is permitted by BS 7671.

Yes. The particular requirements of BS 5839-6 take precedence over the general requirements of BS 7671.

Regulation number(s):

• 110.1

Appendix 15 is intended to give guidance only. Such connection is not prohibited, provided that no part of the ring final circuit will be overloaded as a result.

Regulation number(s):

433.1.204

If the metallic structure falls within the definition of an extraneous-conductive-part given in Part 2 of BS 7671, it is required to be main bonded.

Regulation number(s):

• 411.3.1.2

Regulations 134.1.1 and 510.3 state that manufacturers’ instructions are to be taken into account during installation work. It is necessary to check that all connections are tight, and the use of a torque screwdriver is one way of confirming this.

The limit of zone 1 horizontally is 1.2 m from the centre point of the fixed water outlet (the end of the rigid pipe of the fixed water installation) on the wall or ceiling, irrespective of whether the shower head is fixed or on the end of a flexible hose. Beyond zone 1, the general rules of BS 7671 apply, including Regulation 512.2 concerning external influences. In particular, the IP rating of any electrical equipment must be adequate.

Note: There is no zone 2 for showers without a basin.

Regulation number(s): 

• 701.32.3
• 512.2

Soft-skinned cables to BS 7629-1: 2008 would be exempted from the separation requirements as they have a metallic screen and their survival in a fire has been tested in accordance with BS EN 50200. However, cables to BS 8436: 2004 would not be exempted as the product standard does not require their fire resistance to be tested. Irrespective of the above, BS 5839-1 recommends that, for a fire detection and alarm system complying with that standard, the circuits of fire alarm systems should be segregated from the cables of other circuits to minimize the potential for those other circuits to cause malfunction of the fire alarm system.

Regulation number(s):

• 560.7.7

Yes.

Yes, so long as all the other applicable requirements of BS 7671 are met, including those for protection against overload and short circuit.

Regulation number(s): 

• 411.4.4
• 411.4.5
• 411.4.204

Yes, the requirements for mounting height are different for each of the devolved governments as follows:

England – Approved Documents P and M call for consumer units to be mounted so that the switches are 1350-1450 mm above finished floor level.

Wales – Approved Documents P and M do not provide specific information on mounting height for consumer units but controls that require close vision are required to be located between 1200-1400 mm above finished floor level.

Scotland – Technical Handbook D10 does not provide specific information on mounting height for consumer units but requires electrical controls (which would include consumer units) to be positioned not more than 1200 mm above floor level, unless the need for a higher location can be demonstrated. Whilst there is no minimum height indicated it would seem sensible to locate consumer units at least 900 mm above floor level (the lower limit for light switches).

Northern Ireland – Technical Booklet R does not provide specific information on mounting height for consumer units but for controls that require close vision are required to be located between 1200-1400 mm above finished floor level.

The British Electrotechnical and Allied Manufacturers’ Association (BEAMA) recommend that for a multi-row consumer unit where compliance with mounting heights of ADM1 above cannot be achieved for all switches thereof, the consumer unit should be mounted such that the bottom row of switches are located between 1350 mm and 1450 mm so that they are out of reach of young children to avoid interference and inappropriate operation.

No, unless the cupboard door does not effectively limit the extent of the location. However, where an airing cupboard opens into zone 1 or zone 2, we recommend that circuits supplying equipment in the airing cupboard are provided with additional protection in accordance with Regulation 415.1.1.

Regulation number(s): 

Yes, provided the switch is located so as to be readily accessible and convenient for use.

Generally, cooker switches and cooker control units are provided as a local means of isolation and switching off for mechanical maintenance.

In most cases, the controls incorporated in a cooker can be used to remove the source of heat if danger arises.

However, a cooker switch or cooker control unit may also be provided as a means of emergency switching if the designer of the electrical installation decides that it is necessary, in which case it must be located so as to be readily accessible and convenient for use.

Yes, although it is recognised that the requirement may be difficult to comply with in some situations. 

Not necessarily. Not all types or designs of push fit (screwless-type) clamping units comply with the requirements of Regulation 526.3 (vi).

If the connector will be inaccessible when the installation is complete, it must comply with BS 5733 for a maintenance-free accessory, be marked with the ‘MF’ symbol indicated in Regulation 526.3 (vi), and be installed in accordance with the manufacturer's instructions.

BS 5733 requires, for example, tests for resistance to ageing, cyclic loading, overload, fault current and vibration.

Yes, but certain restrictions apply if the space under the bath or shower is accessible without using a tool because the space is then classed as zone 1.

In zone 1, any low voltage current-using equipment (such as a booster pump for a shower) must be fixed and permanently connected, and the manufacturer’s instructions must confirm that is suitable for installation in that zone.

As with any other item of equipment installed in zone 1, the accessory used to connect it to the supply would need to provide a degree of protection of at least IPX4.

Regulation number(s):

• 701.32.3
• 701.512.2
• 701.55

Yes.  As the space under the bath or shower is accessible only by means of a tool, the space is classed as being outside the zones (Regulation 701.32.3 refers).

Consequently, low voltage current-using equipment (such as a shower booster pump) installed in the space need not be permanently connected, and it may therefore be connected by means of a plug and socket-outlet installed in the space.

Regulation number(s):  

• 701.32.3

Electrical Safety First's Best Practice Guide No 1 (Replacing a consumer unit in domestic and similar premises) sets out a procedure to help avoid such foreseeable circumstances.

In any event, the shared neutral situation must be corrected to remove the electric shock hazard.

Preferably each circuit should be provided with its own neutral to satisfy Section 314.

However, where this is not practicable, the two lighting circuits sharing the neutral may be connected to a single protective device (creating a single circuit), provided that the circuit is suitable for the connected load.

Regulation number(s):

• 314

Yes, where documentation is obtained from the consumer unit manufacturer confirming that the specific mounting orientation is suitable and complies with BS EN 61439-3. Where catalogue products cannot fulfil the installation requirements, manufacturers can be contacted to discuss tailored solutions.

It is essential that any label, RCD test instructions etc remain legible.

Regulation number(s): 

• 510.3
• 511.1

The switch requires clear labelling or indication for the ON and OFF positions, regardless of orientation.

Yes, in certain circumstances. Distributors generally accept a maximum of 2m or 3m from the service head. Where the tails need to be longer, the distributor may require a means of isolation and/or a protective device to be provided within 2m or 3m of the service head. Any particular requirements should be ascertained in advance from the distributor.

Yes. The close proximity of the cold water pipe to the wiring system is unlikely to be detrimental to the cable, for example due to heat or condensation.

Regulation number(s):

Usually not. Manufacturers’ instructions for consumer units and distribution boards generally advise against this for technical reasons (such as potential overheating). Equipment from different manufacturers should not be mixed unless documentation is obtained from the consumer unit or distribution board manufacturer which confirms that the specific mixed arrangement is suitable for use in an assembly conforming to BS EN 60439-3.  Further guidance can be found at www.beama.org.uk

Regulation number(s): 

BS 7671 does not define a dimension to qualify “simultaneously accessible” with respect to supplementary bonding.

However, with respect to prevention of unintentional contact with live parts, the note to 417.3.1 states that two parts are deemed to be simultaneously accessible if they are not more than 2.50 m apart.

Therefore, it is reasonable that with respect to supplementary bonding, parts greater than 2.50 m apart may be considered not to be simultaneously accessible.

Although there is no specific requirement for this in BS7671, account should be taken of the manufacturer's installation instructions, which may or may not require such protection.

Any installation instructions considered to be technically unsound should be queried with the manufacturer and/or referred to the electrical contractor’s registration body for information.

Main protective bonding is required between each metallic branch as it enters an apartment and the Main Earthing Terminal in that apartment, unless it has been proven that the metallic pipework is not an extraneous-conductive-part.

Regulation number(s):

544.1.2

Yes, provided that the distribution board or consumer unit conforming to BS EN 60 / 61439-3 is fitted with blanks that are firmly secured in place with sufficient stability and durability to maintain the required degrees of protection and appropriate separation from live parts under normal service conditions. Distribution board or consumer unit manufacturers can supply blanks to meet these requirements.

Note 1: Different manufacturer’s blanks are not automatically interchangeable. Different types of blanks may be specified by the distribution board or consumer unit manufacturer for specific product references, covering old and new ranges. BS 7671 does not deal with requirements for the construction of assemblies of electrical equipment, which are required to comply with appropriate standards. Therefore, the distribution board / consumer unit should conform to the relevant product standard and be installed according to the manufacturer’s instructions; including any clip-in blanks required to complete the enclosure.

Note 2: Metal blanks should be used only where the consumer unit / distribution board manufacturer has confirmed they are suitable for the intended use.

Regulation number(s):

113.1
134.1.1
416.2.3

No attempt should be made to make a bonding connection directly to semi-rigid pipework.

(a)    Where the gas meter is installed inside the premises, the semi-rigid pipework will normally end at the meter and so the bonding connection should be made as normal to the consumer’s hard metal pipework after the meter and before any branch pipework. Where practicable the bonding connection should be within 600 mm of the meter outlet union.

(b)    Where the meter is external to the premises in a wall-mounted or semi-concealed meter box, the bonding connection should be made to the consumer’s hard metal pipework and before any branch pipework. Where practicable this connection should be made at the point of entry to the building.

Regulation number(s):

411.3.1.2(i)
544.1.2

Where, by design, fault protection is provided by a fuse, circuit-breaker or the overcurrent characteristic of an RCBO, the maximum Zs permitted by BS 7671 for U0 of 230 V can be taken from Table 41.2, 41.3 or 41.4, as applicable.

Where, by design, fault protection is provided by an RCD or the RCD element of an RCBO, the maximum Zs permitted by BS 7671 for U0 of 230 V can be taken from Table 41.5.

It should be noted where fault protection is provided by an RCD then an overcurrent protective device shall provide protection against overload and/or short-circuit current. 

Regulation number(s):

411.4.4

411.4.5

411.4.204

Yes.

Any low voltage circuits passing through, but not serving, zone 1 or Zone 2 of the location must be provided with additional protection by RCD.

Regulation number(s):

701.411.3.3

No. An excessively high external earth loop impedance value would need to be brought to the attention of the Distribution Network Operator (DNO).

Regulation number(s):

N/A

BS 7671 does not specify a minimum distance between an accessory and a heat source, such as a hob.  However, indent (ii) of Regulation 522.2.1 recognises placing sufficiently far from the source of heat as one method that may be used to protect a wiring system.

When considering what constitutes a suitable distance, it is worth remembering that the sources of heat on a cooker top are usually somewhat inboard from the edge of the appliance.  Another point to remember is that the integral control dials on a cooker are in some cases significantly closer to the source of heat than any accessory affixed to the building fabric, and they do not suffer significant heat damage.

An accessory installed at least 100mm horizontally from the edge of the hob is likely to meet the requirements of BS 7671.  If an accessory is encountered closer to a hob than this during a periodic inspection, engineering judgement will need to be applied to determine whether this is safe. An accessory so located for a considerable time that had not suffered any perceptible heat damage would not warrant a classification code or comment on the Electrical Installation Condition Report.

Any manufacturer’s recommendations should be taken into account.
An accessory should not be located immediately above an electric oven or hob due to the possibility of people reaching over suffering burns or the flexible cable of connected equipment being damaged.

Regulation number(s):

522.2.1

No (with one specific exception). Single-core cables having green-and-yellow insulation must not be overmarked or otherwise identified, and must not be used for any purpose other than a protective conductor. The only exception is where such a cable is used as a PEN (combined protective and neutral) conductor, when blue markings must be provided at the terminations.

Regulation number(s):

514.4.2
514.4.3

BS 7671 does not specify a minimum height or horizontal distance.  However, Regulation 512.2.1, relating to external influences, requires that equipment shall be of a design appropriate to the situation in which it is to be used or its mode of installation shall take account of the conditions likely to be encountered.

Regulation 522.3.1 requires a wiring system to be selected and erected in such a way that no damage is caused by condensation or by ingress of water whilst being installed, used or maintained.

When installing standard accessories, good practice would be to install them at least 300 mm horizontally from the extremity of the sink bowl (excluding drainer) or wash basin opening. 

For commercial premises, the same principle applies.  However, the designer may consider it appropriate, due to the increased risk of splashing or the use of water jets, to install equipment that has a degree of protection of at least IPX4 or IPX5 respectively, as appropriate.

If an accessory is encountered closer to a sink than this during a periodic inspection, engineering judgement will need to be applied to determine whether this is safe. An accessory so located for a considerable time that had not suffered any perceptible water ingress or damage would not warrant a classification code or comment on the Electrical Installation Condition Report.

General guidance is to avoid positioning a consumer unit immediately above or alongside a sink.

Regulation number(s):

512.2.1
522.3.1

It is indeterminate which of the above regulations should be applied where the sloping surface might reasonably be considered to be either a wall or a ceiling. Nevertheless, it is still necessary to comply with the fundamental requirements of BS 7671 for protection of a wiring system against impact, which are given in Regulations 522.6.1 and 522.6.2.

One way of meeting these fundamental requirements in the case of a sloping surface that could be either a ceiling or a wall is to design the part of the installation concerned to meet the requirements of Regulation 522.6.201 and 522.6.204 and the requirements of Regulations 522.6.202 to 522.6.204.

Regulation number(s):

522.6.201
522.6.202
522.6.203
522.6.204

If an existing circuit of a location containing a bath or shower is extended, at least the extended part of the existing circuit must be provided with RCD protection. Supplementary bonding in a bathroom or shower room must be provided unless all the requirements in BS 7671 for the omission of supplementary bonding are met.

Regulation number(s):

701.411.3.3
701.415.2

The preferred option is to provide RCD protection for the circuit at the origin as this gives an improvement in safety for the whole circuit.

Alternatively, an RCD protected, switched, fused 13 A connection unit could be added directly adjacent to the existing outlet from which the extension is being taken.

Regulation number(s):

522.6.202 to 522.6.204

Any alteration or addition to an existing installation must comply with the current edition of BS 7671 (including any amendments). This requires any earthing and bonding arrangements upon which the alteration or addition relies for safety to be adequate. Adequate earthing or bonding is not required where the alteration or addition does not use this as part of the protective measure, e.g. double or reinforced insulation. See also Q1.76 and Q1.77.

Regulation number(s):

132.16

411.3.1.1

644.1.2

Additional protection by RCD is a requirement for low voltage cables concealed in a wall at a depth less than 50 mm from the surface of a wall or partition, or concealed at any depth in a partition the internal construction of which contains metallic parts.

RCD protection for low voltage cables so installed in a wall or partition may only be omitted where the cables:

Incorporate an earthed metallic covering which meets the requirements of BS 7671 to be a protective conductor, or
Are installed in earthed conduit, trunking or ducting which meets the requirements of BS 7671 to be a protective conductor, or
Are provided with mechanical protection sufficient to prevent damage of the cable from fixings such as nails and screws. 

Regulation number(s): 

522.6.202
522.6.203
522.6.204

Yes. There should be more than one RCD, and the circuits should be divided between them in order to minimize the likelihood and consequences of tripping.

Regulation number(s):

314.1

No. Such maintenance or repair work would not be classified as an alteration or addition.

Regulation number(s):

411.3.3

No. Such repair work would not be classified as an alteration or addition.

Regulation number(s):

For guidance on what constitutes an alteration or addition see note to definition for Minor Works in Part 2 of BS 7671.

No, unless RCD protection is recommended by the manufacturer’s installation instructions or a new circuit is required (to provide for increased load, for example).

In cases where the existing consumer unit is of a type that will permit the replacement of an existing circuit-breaker by an RCBO of appropriate type and rating for the circuit in question, the installer may wish to explain the benefits of improved safety provided by carrying out such a, relatively speaking, simple upgrade.

Regulation number(s): 

134.1.1
510.3

Supplementary bonding would be required for any new extraneous-conductive-part installed in a bathroom or shower room unless all the other requirements of Regulation 701.415.2 have been met.

Regulation number(s):

701.415.2

Where socket-outlets are in areas liable to be used by persons of capability BA1 (Ordinary), BA3 (Disabled) or children (BA2, BA3) or are provided for mobile equipment with a rated current not exceeding 32A for use outdoors, additional protection by RCD must be provided.

In any other circumstances additional protection by an RCD may only be omitted for mission-critical or life-safety purposes where a suitably documented risk assessment produced by the elected duty holder (person having significant control) with the involvement of a skilled person (electrically) determines that it is not necessary.

The specific application of the socket-outlet(s) should be recorded on the risk assessment.

The documented risk assessment must  be appended to the appropriate electrical installation certificate.

Regulation number(s):

411.3.3

Not necessarily. If the existing 6 mm² bonding connects all the extraneous-conductive-parts to the main earthing terminal, has been in place for a significant time and shows no signs of thermal damage, then it may not require to be upgraded.

Regulation number(s):

132.16
544.1.1

Regulation 462.1.201 requires a main linked switch or linked circuit-breaker to be provided as near as practicable to the origin of every installation as a means of switching the supply on load and as a means of isolation.

However, it is permitted for a dwelling to have more than one electrical installation. Regulation 462.1 requires means to be provided to isolate each electrical installation from each supply. Therefore a further ‘main switch’ is not required to isolate both consumer units.

Regulation 537.2.7 requires each device used for isolation to be clearly identified by position or durable marking to indicate the installation it isolates.

Regulation number(s):

462.1

462.1.201

537.2.7

No. As the new work must comply with BS 7671, fault protection must be provided by an overcurrent device or RCD, and additional protection, where required (such as for socket-outlets or cables concealed in walls), must be provided by a 30 mA RCD.

No.

Yes, because the work would be more than a like-for-like replacement.

Regulation number(s):

701.411.3.3

No, not without additional mechanical protection.

You should make your customer aware of the issues relating to accessibility, including the need to test RCDs at quarterly intervals, to enable the customer to make an informed decision about the position of the replacement consumer unit.

Regulation number(s):

132.12

513.1

All accessible exposed-conductive-parts and extraneous-conductive-parts are required to be connected to the same earthing system individually, in groups or collectively. This means that the main earthing terminals must be connected together.

Yes, but only where the manufacturer's instructions confirm that the switch has been designed for this purpose.

Yes.

Regulation number(s):

132.16

Yes.

Regulation number(s):

132.16

No, as this may result in unearthed parts of the existing installation and earthed parts of the new circuit being simultaneously accessible. This is not permitted by Regulation 411.3.1.1.

In any event, whenever an alteration or addition is carried out to an existing installation, it shall be verified that the alteration or addition complies with the Regulations and does not impair the safety of the existing installation.

Regulation number(s): 

411.3.1.1
641.5

Where additional protection by RCD is necessary, unwanted tripping can be avoided by appropriate sub-division of circuits.

Regulation number(s):

314.1
531.3.2

Reference should be to the applicable Building Regulations, BS 5839-1 and BS 5266 which give specific recommendations.

No. An RCD is a valid way of complying with automatic disconnection requirements.

Regulation number(s):

411.3.2.2

411.3.2.3

411.3.2.4

411.4.5

415.2

No. BS 7671 requires all extraneous- and exposed-conductive-parts that can be touched by livestock to be supplementary bonded, whether or not the parts are simultaneously accessible.

Regulation number(s):

705.415.2.1

No. Section 717 applies to transportable units that are intended to be moved relatively frequently from place to place and which therefore need to be supplied through flexible cables.

Regulation number(s):

717.1

At the location of the equipment which cannot be disconnected in the prescribed time. Consideration must be given to disconnection required for reasons other than electric shock, for example, overcurrent protection.

Regulation number(s):

411.3.2.5
415.2
419.3

Yes. However, it should be borne in mind that disconnection may be required for reasons other than protection against electric shock.

Regulation number(s):

411.3.2.5

No. The above cable does not meet indent (ii). To comply with indent (iii), duplicate protective conductors would be required. Alternatively, the solutions offered by indent (iv) or (v) could be adopted.

Regulation number(s):

543.7.1.203

a) Yes, except where the cable management system is not an exposed-conductive-part. (The steel wire armour of a cable is considered to be an exposed-conductive-part.)

b) No. There is no requirement to calculate or select the cross-sectional area of an exposed-conductive-part unless it intended to be used as a circuit protective conductor.

Regulation number(s):

411.3.2.1
543.1.1

As a minimum a certificate for initial verification, complete with the Guidance for Recipients shall be provided to the person ordering the work.

Relevant information should be recorded on the appropriate certificate;

For a MEIWC:    Part 1 Section 5
For an EIC: Schedule of Test Results – Remarks Column

or, as a separate attachment, to either of the above.

Note: 514.9.1 now contains certain exceptions for diagrams and documentation for domestic premises and similar.

Regulation number(s):

514.9.1

Appendix 6

Yes. The armour provides suitable protection against mechanical damage.

Regulation number(s):

543.7.1.203 (ii)

Primarily the chassis. Any structural metal parts connected electrically to the chassis would be effectively bonded. Any structural metal parts not connected electrically to the chassis would be isolated, and would therefore not need to be bonded for reasons of safety.

Regulation number(s):

Part 717

717.411.3.1.2

No. If the tables are not liable to introduce a potential, generally Earth potential, they will not require main bonding.

A dry assembly area would not be considered to be a location of increased shock risk, so there is no requirement for supplementary bonding.

The tables are not items of electrical equipment, so there is no requirement for them to be earthed.

Regulation number(s):

411.3.1.1

411.3.1.2

415.2 Note 4

Yes. Table 52.3 refers to Section 715 for ELV lighting. Regulation 715.524.201 states that the conductor size is dependent on the load current except where luminaires are suspended from and supported by the conductors, in which case a minimum conductor size of 4mm2 applies.

If the installer decides to use conductors smaller than those permitted by Table 52.3 and Regulation 715.524.201, this would need to be noted as a departure in the Electrical Installation Certificate (Regulation 120.3 refers).

Where a departure is noted in an Electrical Installation Certificate, the designer and/or installer is declaring that the resulting degree of safety of the installation will be not less than that obtained by compliance with the relevant requirements of BS 7671.

ELV cables fitted with plugs and sockets supplied as part of a prefabricated CE-marked LED lighting system (comprising driver, LED lights and interconnecting cables) are assemblies of electrical equipment and are therefore not subject to the minimum cross-sectional area requirements of BS 7671.

Regulation number(s):

113.1

Table 52.3

715.524.201

Guidance can be found in the Health and Safety Executive’s publication HSG 47 Avoiding danger from underground services, which can be downloaded free of charge from the HSE website.

Yes, however, Regulation 512.1.5 requires that such equipment shall not be connected to conductors intended to operate at a temperature exceeding 70° C at the equipment in normal service unless:

the equipment manufacturer has confirmed that the equipment is suitable for such conditions (see Note b of Table 52.1 and Note 3 of Table 4G2A for mineral insulated cables with a sheath operating temperature of 105 °C), or

the conductor size is chosen based on the current ratings for 70 °C cables of a similar construction* (see Regulations 526.2, 523.1, 536.4.202 and Table 4A3 Tables 4D1 to 4D5 and 4H1 to 4H4).

Where the current rating of the cable is to be based on 70° C, current – carrying capacities given in Tables 4D1 to 4D5 and 4H1 to 4H4 of Appendix 4 may be used for 90° C thermosetting insulated cables

Regulation number(s):

512.1.5

523.1

526.2

536.4.202

Tables 4D1  to 4D5

Tables 4H1 to 4H4

Protective neutral bonding (PNB) like protective multiple earthing (PME) is a variant of a TN-C-S system, but unlike PME the combined neutral and earth (CNE/PEN) conductor is connected to Earth at one point only.

For a PNB supply, some Distribution Network Operators (DNOs/Distributors) permit the main protective bonding conductor(s) to be sized as for PME; whereas others permit it to be sized as for TN-S.

However, as  advised by the Note above Table 54.8 of BS 7671, designers should always confirm any particular requirements of the relevant local DNO as it may require a larger size of protective bonding conductor to take account of local network conditions.

Regulation number(s):

544.1.1

Table 54.8

Guidance on this can be found in Clause 6.2.5 of Engineering Recommendation G12 Issue 4 (2013) Requirements for the Application of Protective Multiple Earthing to Low Voltage Networks published by Energy Network Association (ENA).

Where it has been decided to use a PME supply, and where the distributor agrees to such use, all the appropriate requirements within Section 702 of BS 7671 must be met.

There is no specific requirement in 421.1.201 for fire-rated cable glands or intumescent sealant to be used for cable entries.

Good workmanship must be applied in particular to limit openings around cables to a minimum. In any case, the requirements of regulation group 416.2 for barriers or enclosures must be met.

Manufacturers’ instructions, if any, should be taken into account.      

Regulation number(s):

134.1.1

421.1.201

Regulation group:

416.2

510.3

The term ‘escape route’ is defined in Part 2 of BS 7671 as the ‘path to follow for access to a safe area in the event of an emergency’.

Communal corridors and stairways located in industrial and commercial buildings and blocks of flats are examples of escape routes.

In domestic premises examples include passageways and staircases that are the sole means of exiting in an emergency other than escaping from an emergency escape window.

Regulation: Part 2

It is defined in Part 2 of BS 7671 as ‘A route enclosed with specified fire-resisting construction designed for escape to a place of safety in the event of an emergency’.

The decision as to what is a  ‘protected escape route’ will be made by a person competent in fire safety engineering design for the particular building.

Regulation number(s):

Part 2

422.1

422.1.1

422.1.2

422.1.3

Appendix 13

Yes, BS 7671 includes requirements for the fixed wiring for information and communication technology, signalling, control and the like (see indent (vi) of Regulation 110.1.2).

Regulation number(s):

110.1.2

Yes, so long as within the consumer unit:

its rating and condition is adequte for the altered circumstances, and
all existing conductor connections are correctly located in terminals and are tight and secure, and
there are no signs of overheating, and
no incorporated equipment is subject to a product recall.

Regulation number(s):

132.16
526.1

On the schedule of inspections for new installation work only, item 7.5 should be marked as not applicable (N/A) because it is not a newly installed item of equipment.

Within the ‘Comments on existing installation’ section on the Electrical Installation Certificate a statement should be made that:                                                           

 ‘N/A’ has been recorded against item 7.5 of the schedule of inspections because the addition has been made to a consumer unit that was installed to the requirements of an earlier edition of BS 7671 and has been verified to be adequate for continued use.

Regulation number(s):

132.16

Wiring systems, whether cables clipped direct, conduit, trunking or similar should be supported in accordance with the recommendations of the manufacturer.

Regulation number(s):

510.3

Yes, subject to such construction being suitable for ambient environmental conditions such as:

likelihood of mechanical damage, 
use of outbuilding for storage of flammable materials such as paint and thinners, or 
presence of a corrosive atmosphere, such as that found in a swimming pool pump room.

Consideration should also be given to the relative proximity of the outbuilding to the dwelling with respect to the possibility of fire-spread from one structure to the other.

No. Suitable fire-resistant means of support or retention should be provided to prevent wiring systems impeding movement in the event of a fire.

The easiest way of achieving this is for all supports to be of a type unaffected by fire.

Where it is decided to not use only fire resistant supports, this will require careful assessment of the individual circumstances.

Regulation number(s):

521.10.202

No.

No. Manufacturers’ instructions, if any, should be taken into account

Not necessarily. Manufacturers of trunking systems will be able to advise on making their trunking compliant with Regulation 521.10.1.      

In general, a system assembled properly from compatible parts such as trunking, lids, tees, bends and other accessories will comply, as could a system containing well-made site-fabricated bends although it should be noted that some contracts or specifications will not permit the use of site manufactured bends.

Regulation number(s):

416.2.2
521.10.1

No.

A sheathed cable can be passed through a suitably sized hole drilled through an external wall without sleeving. Reasonable steps should be taken to ensure that the cable is not damaged during installation.

It is recommended that any such hole is angled downwards so outside hole is lower than that on inside and the space between hole and cable is suitably stopped to prevent moisture penetration.

Regulation number(s):

522.3.1
522.8.1

It is necessary to confirm that the rating and condition of any existing electrical equipment, including that of the distributor / supplier will be adequate for the altered circumstances, such as any increase in electrical loading that the addition/alteration introduces.

It is also necessary to confirm the adequacy, in relation to protection against electric shock, of the earthing and bonding arrangements.

Regulation number(s):

132.16 
642.2

BS 7671 does not specifically require the provision of a local means of disconnection to be provided for appliances.

However, many manufacturers of built-in appliances recommend that a means of disconnecting the appliance should be accessible when the product is installed; therefore it is advisable to request any special installation instructions pertinent to their equipment from those supplying such equipment.

Yes. Engineering Recommendation G12-3 published by the Energy Networks Association permitted Distribution Network Operators (DNOs) to install BS 951 clamps on the sheath of a cable. G12-4, published in 2013, now permits DNOs to use clamps which comply with EREC C93. So, both BS 951 and other clamps may be encountered on the sheaths of service cables.

On no account should an electrical contractor fit a clamp to the sheath of a service cable.

Before starting any electrical installation work or when carrying out a periodic inspection of an installation, the electrician must confirm that the earthing facility is sufficient in terms of the requirements of BS 7671.

One way to verify the adequacy, or otherwise, of such a connection is to carry out a measurement of the impedance of that part of the earth fault loop external to the installation (Ze) at:

the cable sheath, and
the clamp.

The two readings obtained should be substantially the same.

Typically, the maximum impedance of that part of the earth fault loop external to the installation (Ze) is 0.8 Ω. However, due to network conditions this value is sometimes exceeded.

Responsibility for ensuring the safety and effectiveness of this connection rests with the DNO (Regulation 24(1) of the Electricity Supply Quality and Continuity Regulations (ESQCR)). 

The electrician should advise the customer to contact the relevant Distribution Network Operator (DNO) and request that the ineffective connection on their equipment is rectified. The DNO may be able to provide a TN-C-S earth to the property although there may be a charge to do so.

Alternatively, the electrician can offer to convert the system earthing to TT through installation of earth electrodes and any required RCD protection.

On no account should:

any attempt be made to further tighten, connect, disconnect any such clamp encountered on the sheath of a service cable.
the contractor attempt to fit a clamp to the sheath of a service cable.

No. Note 1 of 421.1.201 gives ferrous metal as an example of a non-combustible material. The cabinet or enclosure can be made of other non-combustible materials. However, the installer will need to judge whether such material used will provide adequate protection. Account will also need to be taken of Regulation 132.12 in relation to accessibility.

Regulation number(s):

421.1.201 (ii)

Buried cables, conduits and ducts shall be at a sufficient depth to avoid being damaged by any reasonably foreseeable disturbance of the ground.

A depth of 0.5m is recommended as sufficient to avoid damage by general gardening.

Where more onerous conditions are present due to, for example,  ground cultivation then greater depths should be used.

All buried cables should be identified with a warning tape or cable covers above the cable.

It is strongly recommended that the route of a buried cable should be identified on a drawing attached to the Electrical Installation Certificate.

Regulation number(s):

522.8.10

Yes.

The circuits and also the conductors of each circuit within the multicore cable would need to be suitably identified to permit inspection, testing, repair or alteration.

Whilst it would be permissible for the multiple circuits to share a common CPC such as the armouring of an SWA cable, it would not be permissible to share a neutral.

Where circuits are at different operating voltages, each conductor must be insulated for the highest voltage present.

When considering current carrying capacity, Table 4B5 of BS 7671 contains rating factors for cables having more than four loaded cores.

Regulation(s) 514 group; 521.7; 528.1; Table 4B5.

Yes.

Where water connection valves serving appliances such as washing machines and dishwashers are present, socket-outlets should be so placed that water from these valves or hoses connected to them is unlikely to affect the socket-outlet or plug during connection or disconnection of the appliances.

No. Regulation 421.1.201 relates to consumer units and similar switchgear assemblies complying with BS EN 61439-3 Low voltage switchgear and controlgear assemblies.  Distribution boards intended to be operated by ordinary persons (DBO). 

Switch-disconnectors (both AC and DC), otherwise known as isolating switches, are designed and manufactured to a different standard -  BS EN 60947-3 Switches, disconnectors, switch-disconnectors and fuse-combination units and therefore are not subject to this requirement unless they are incorporated within a consumer unit or similar controlgear assembly.

This does not preclude the specification or use of switch-disconnectors having non-combustible / metal enclosures.

Regulation number(s):

537.1

Table 537.4

Appendix 1

No, however this does not preclude its use. 

Protective bonding is only required where the pipework is an extraneous-conductive-part. Such protective bonding should be applied as near as practical to the point of entry of that pipework to the building.

No.

Regulation number(s):

411.3.1.2

When it is proved to be an extraneous-conductive-part.

Regulation number(s):

411.3.1.2

Yes, provided all relevant design criteria is verified as suitable.

Regulation number(s):

Sections 311, 312, 313, 314 and Appendix 15

Yes, the requirements in 544.2 apply to all supplementary bonding conductors.

Regulation number(s):

415.2
544.2

It is impossible to give an exact generic figure in terms of recommended service life. This is due to a number of factors.

As an indication as to whether the device is in a satisfactory condition for continued service, it must be manually operated and examined to validate that it is of the correct type and ratings and has no signs of thermal / mechanical damage, arcing or overheating.

Regulation number(s):

CH 65 - Appendix 6 condition report inspection schedule (4.8, 4.14)
Electrical Safety First Best Practice Guide 4

Irrespective of the age of the BS 3871 equipment, a code or comment is not required provided there is no deterioration, defect, or non-compliance with the current edition of BS 7671 that may give rise to danger. 

CH 65, Appendix 6 condition report inspection schedule (4.8, 4.14)

Electrical Safety First Best Practice Guide 4

Yes.

However, it is essential to confirm that the measured value of Zs is not indicative of a defect, such as a loose connection or an inadequate means of earthing.

Regulation number(s):

411.4.4

411.5.2

Yes. Properly selected and installed plastic wall plugs can be used to support cables, wiring systems and the like.

No.  Appendix 1 includes only those standards which are included in BS 7671 and Appendix 4 is informative not normative.    

Split concentric cable in the LV range complying with either one of two British Standards - BS 4553 and BS 7870 - may be selected, if appropriate to the intended use, without infringing the requirements of BS 7671.      

Split concentric thermoplastic insulated and sheathed cable is listed in Table F4 of IET Guidance Note 1, Selection and Erection as one of the types of cable that can be used for fixed wiring.

Split concentric cables can be used in consumers' premises, provided they comply with the relevant cable standard and are installed in accordance with the requirements of BS 7671.  Some types of terminal and clamping unit are unsuitable for the multiple neutral conductors of split concentric cable.  Consequently, installers must take account of instructions for terminations provided by the manufacturer of the distribution board / consumer unit.  

Regulation number(s):

133.1.1
510.3
511.1

No, there is no defined maximum limit of resistance stated within BS 7671. However, there is a requirement to verify continuity by measurement. The measured value need not be recorded.

Regulation number(s):

544.1.1
643.2.1

Yes.

Note: Devices to BS 7288: 1990 will be of RCD type AC. Devices to BS 7288: 2016 will be of type AC or type A, with the type marked on the product.

Regulation number(s):

531.3.4.1

531.3.4.2

No. Regulation 411.3.4 applies to circuits supplying luminaires. Extending an existing circuit to supply a smoke alarm does not affect the protective measures for the existing circuit. Therefore, RCD protection is not necessary with respect to Regulation 411.3.4.

However, other requirements relating to RCD protection shall be met where necessary e.g. for a cable concealed in a wall at insufficient depth.

Regulations:

132.16
411.3.4
522.6.202
522.6.203

No, BS 7671 refers to several precautions that could be applied to prevent unintentional or inadvertent closure such as: located within a lockable space or lockable enclosure, padlocking, located adjacent to the associated equipment.

Regulation number(s):

462.3
464.2
537.2.4

OCPD 2 may be omitted where all of the following apply:
• The SPD is in a household or similar installation
• The SPD conforms to BS EN 61643-11
• The SPD manufacturer’s instructions state that OCPD 2 can be omitted, and specify the required OCPD 1 characteristics (typically the cut-out fuse has a rating not exceeding 125 A)

Regulation number(s):
134.1.1
361.1
534.4.5.1
534.4.5.2
534.4.5.3
Fig 534.5

When OCPD 2 is required according to the SPD manufacturer’s instructions, partial or total selectivity should be verified between OCPD 2 and OCPD 1.

Account should be taken of the SPD and OCPD manufacturer’s instructions.

Regulation number(s):

134.1.1

361.1

534.4.5.1

534.4.5.2

534.4.5.3

Fig 534.5

Whilst a meter cabinet is owned by, and is the responsibility of, the homeowner, the space within the cupboard is designed for the use of electricity industry apparatus only, and no allowance is made for additional equipment to allow safe access for maintenance or replacement.  For this reason, it is strongly recommended that such items of electrical equipment are not installed within a meter cabinet.

Link to government guidance as below:

Smart metering for domestic new builds: guidance for developers and architects (publishing.service.gov.uk)

A: Yes, for reasons as described in Best Practice Guide 3, figure 2: this requirement was originally introduced in BS 7671:2008 17th Edition.

Regulation number(s):

522.6.202

522.6.203

551.7.1

Only if the metallic pipework is an extraneous-conductive-part.

Part 2 Definitions (extraneous-conductive-part), Regulation 411.3.1.2 and 544.1.2.

No.

A method of verifying whether a conductive part is an extraneous-conductive-part would be to carry out resistance testing using an insulation resistance tester at 500 V DC, between the MET and the conductive part.

Depending on the safe level of current deemed acceptable, the minimum resistance value where bonding would not be required could be within a range of 6.67 kΩ - 22 kΩ.

The table below gives indicative values depending on example levels of current:

Note: Other verification methods may be suitable.

Part 2- Definitions, (Extraneous-conductive-part)
Regulations: 411.3.1.2, 643.1

Yes, a separate DC isolator should be provided, unless the inverter provides DC isolation conforming to Table 537.4 including Note 1.

Note: Where connectors conforming to BS EN 62852:2015+A1:2020 are not utilised in the connection of the inverter, a separate DC isolator shall be provided.

Table 537.4

Regulation: 712.537.2.101

As defined in BS 7671:2018+A3:2024, ‘a unidirectional protective device is a protective device where it is intended by the manufacturer that a source of supply is only connected to one defined set of connection terminals’.
These devices will be marked ‘LINE’ and ‘LOAD’ or ‘IN’ and ‘OUT’ or have directional arrows.

As defined in BS 7671:2018+A3:2024, ‘a bidirectional protective device is a protective device where it is intended by the manufacturer that a source of supply is connected to either or both sets of connection terminals’.
These devices will not be marked ‘LINE’ and ‘LOAD’ or ‘IN’ and ‘OUT’ or have directional arrows.

Link to IET BS 7671:2018+A3:2024 free download: Download your free PDF 'bolt-on': BS 7671:2018 Amendment 3:2024
Part 2
Regulation number 530.3.201

Link to BEAMA document: BEAMA Factsheet - Markings and symbols for Circuit Protection Devices - August 2024

¹An overcurrent protective device includes:

•      A miniature circuit-breaker (MCB) to BS 3871 – withdrawn and
           superseded by BS EN 60898:1991
•      A circuit-breaker (CB) to BS EN 60898
•      A moulded-case circuit-breaker (MCCB) to BS EN 60947-2
•      An air circuit-breaker (ACB) to BS EN 60947-2

²An RCD device includes:

•      an RCCB to BS EN 61008
•      an RCBO to BS EN 61009

No, these requirements do not apply.
 
WRAG members' guidance is based on their understanding of the original intent when developing Regulation 421.1.201 — namely, that the non-combustible requirements apply to assemblies installed within or inside domestic buildings, and not to those located externally or outdoors.
 
The general requirements of BS 7671 for selection and erection of equipment would continue to apply to assemblies installed outdoors.
 
Note 1: Similar switchgear assemblies are assemblies used for the same fundamental application as consumer units. Please refer to the following link for examples of such equipment:
https://www.beama.org.uk/static/uploaded/5eb540ba-e737-4b5f-b498bb2f56fd802b.pdf
 
Note 2: It is strongly recommended that such items of electrical equipment are not installed within a meter cabinet.  Please refer to Q1.137.
 
Note 3: Please refer to Q1.104 regarding the installation of such equipment in a detached outbuilding of a domestic ‘household’ premises.

No. Regulation 421.1.7 does not apply to shaver sockets because these are typically either:
 
• Shaver supply units that conform to BS EN 61558-2-5 and incorporate an isolating transformer, or

• Shaver sockets that conform to BS 4573 and include 200 mA self-protection
 
These configurations provide inherent protection and are not within the scope of Regulation 421.1.7.

The table below provides examples of how this information can be recorded, however other methods are also acceptable:

Note 1: Arc fault detection devices should conform to BS EN 62606:2013+A1:2017
Note 2: * relates to column number in the generic model schedule given in Appendix 6 of BS 7671:2018 (as amended)

There is comprehensive information available in relation to this question in Best Practice Guide 1, covering several circumstances. Link to Best Practice Guide 1 Issue 5.

General guidance on the use of Classification Codes is available in Issue 4 of Electrical Safety First's Best Practice Guide No 4, which may be viewed or downloaded free of charge by clicking here.

Although existing installations need to be assessed against the requirements of the current edition of BS 7671, this does not necessarily mean that they require upgrading, unless a departure from the latest requirements constitutes an immediate or potential danger. However, it would usually be appropriate to recommend improvement by giving the observation a Classification Code C3.

Regulation number(s):

Introduction to BS 7671

You can find them here.

Classification Code C2. Where the presence of supplementary bonding cannot be confirmed by inspection, it may be verified by a continuity test (< 0.05 Ω)

Verification of voltage drop is not normally required unless there is considered to be a voltage drop problem.

Regulation number(s):

643.11

If a VOELCB on a TT system fails to operate when tested with an instrument or integral test button, this would warrant a Classification Code C2 (potentially dangerous).

But, subject to the VOELCB being proved to operate correctly, continued reliance on it for fault protection (protection against indirect contact) would normally warrant a Classification Code C3 (improvement recommended).

However, if the VOELCB relies on a water pipe not permitted by Regulation 542.2.6 to be a means of earthing, this should attract a Classification Code C2 (potentially dangerous).

In any case, the person who ordered the inspection should be advised that the voltage-operated device should be replaced with RCD protection at the earliest opportunity to enhance the safety of the installation. 

Regulation number(s):

542.2.6

This size of tails may be adequate provided the maximum demand of the installation, taking into account the load characteristics (diversity and load profile), does not exceed the current-carrying capacity of the tails, and also provided that the requirements of Regulation 434.5.2 for protection of the tails against fault current are met.

As a practical tip, the current-carrying capacity of the meter tails is likely to be adequate if they have been in service for several years and there are no signs of thermal damage at the terminations or to the cable sheath or insulation.

Regulation number(s):

311.1 
433.3.1(ii) 
434.5.2

This size of earthing conductor will be adequate if the requirements of Regulation 543.1.3 (adiabatic equation) are met.

Regulation number(s):

542.3.1

543.1.3

Regardless of RCD type, a single AC test at the rated residual operating current (IΔn) is to be applied  at 0° or 180°.

Additionally, the continued functionality of the integral test button should be verified.

There is no requirement in BS 7671 to test an RCD at half its rated residual operating current (½IΔn), 5 times rated residual operating current (5IΔn), ramp test, or to test at both 0° and 180° or other tests, although such tests might be useful during fault finding activities.

Regulation number(s):

643.7.1

643.8

Live testing is an essential part of establishing whether an installation is in a satisfactory condition for continued service, which is the purpose of a periodic inspection.

It will be necessary for the live testing to be completed, and therefore for the supply to be available, before an Electrical Installation Condition Report indicating a satisfactory overall assessment can be issued.

Yes

Regulation number(s):

411.3.1.1
411.3.2
643.7

No. In any event, it is not essential to measure (R1 + R2) values for a Condition Report.

No, as it involves avoidable live working (unless the construction of the distribution board provides a suitable form of separation. See the BEAMA Guide to Forms of Separation).

Yes, provided that the continuity test instrument, test leads and probes are in good condition (to avoid the risk of electric shock). This test method should not be used inside enclosures containing live parts that are energized (to avoid the risk of touching a live part with the wander lead probe).

Not necessarily. It depends on whether all the required information for each part of the installation can be recorded on one Condition Report.

In many cases, the covering of cables in thermal insulation, whilst not recommended, does not result in overheating sufficient to damage or degrade the cable insulation or connected accessories, so would not need to be recorded in the Condition Report.

Where there are no signs of overheating, but the conductors are underrated in relation to thermal insulation which could result in potential danger in the future, allocation of a classification code C3 (Improvement recommended) would be appropriate. This is because the conductor current-carrying capacity, under the particular installation conditions concerned, do not conform to the recommendations in BS 7671 appendix 4 and are undersized. The conductor insulation or accessories could slowly deteriorate. The level of such deterioration would be related to the load current magnitude, resulting conductor temperature and its duration.

However, if the inspector has reasonable doubt about the adequacy of the cable rating in relation to the nature of the load (for example there are signs of overheating), such that there is potential danger, a Classification Code C2 (potentially dangerous) would be appropriate.

Regulation number(s):

523.9

Where inadequacies in distributor’s equipment are observed, the contractor should recommend that the person ordering the report requests the distributor or meter operator, as appropriate, to carry out remedial work as necessary to remove the danger or potential danger.

Distributors and meter operators have an obligation under the Electrical Safety, Quality and Continuity Regulations  (ESQCR) to maintain their equipment, so far as is reasonably practicable, to prevent danger.

Regulation number(s):

651.2

It would be necessary to verify that the RCD operates within the criteria stated in the relevant product standard (BS EN 61008-1) and reproduced in Table 3A of Appendix 3 - that is between 130 ms and 500 ms.

The absence of a seal is not an electrical safety issue and so no entry is required on the Condition Report. However, the owner/occupier should be informed that the seal is missing and they should be advised to contact the relevant DNO or meter operator.

The principle of sampling can be employed at both the inspection and the testing stages when carrying out a periodic inspection and testing. 
     
Sampling can never be applied to measures to determine adequacy of:

Incoming supply arrangements
main earthing and bonding 

Whilst a degree of sampling is permitted, it is recommended that the following should be undertaken as a minimum where practical:

an external visual inspection of all accessible electrical equipment (light fittings, switches, socket-outlets etc.)
An internal visual inspection of every consumer unit and confirmation that all conductors are correctly located in terminals and are tight and secure
a close inspection of the terminations and connections at a representative number of items of electrical equipment on every final circuit and, in particular where the external visual inspection has raised concerns
cpc continuity to all accessible exposed conductive parts. Note: An earth fault loop impedance test may be used to confirm  there is a connection to Earth. 
earth fault loop impedance at the origin, every accessible socket-outlet and, so far as can be determined, the furthest point of every final circuit (e.g. a lighting circuit).
Testing all RCDs in accordance with BS 7671.

Regulation number(s):

651.2

In general, electrical installations do not present increased risks of fire in thatched properties.

In the absence of any specific requirements (such as those of the building insurers), there are no particular requirements over and above those for any installation in domestic premises.

As with any other type of property, the recommended period between inspections can be varied at the discretion of the person carrying out the inspection, based on the outcome of the inspection. 

Regulation number(s):

652.1

Either value can be used. However, it is essential to confirm that the measured value of Z_s is not indicative of a defect, such as a loose connection or an inadequate means of earthing.

Regulation number(s):

411.4.4
411.4.5
411.4.204

Where an insulation resistance measurement between live conductors connected together and Earth results in a reading of less than 1 MΩ, a classification code C2 (‘Potentially dangerous’) should be recorded on the EICR.

Subsequent investigation during remedial work would then reveal whether the low insulation resistance was due to a defect or deterioration in the installation, or as a result of connected equipment.

See Electrical Safety First's Best Practice Guide 4 for further details.

An installation should be inspected, tested, verified and certificated to the version to which it was designed.

No, not on its own. Whilst the test can provide an indication of polarity, it needs to be combined with inspection and further testing as required by Part 6 of BS 7671. 

Regulation number(s):

642.3
643.6

To verify that the requirements of Regulation 543.5.1 relating to combined protective and functional earthing, and Regulation 543.7 relating to high protective conductor currents, have been met as appropriate.

Regulation number(s):

543.5.1 
543.7

To confirm that the fault protection arrangements for alternative sources of supply have been met.

Regulation number(s):

551.4

It is necessary to verify that the supplementary provisions described in Regulations 411.7.2 and 411.7.3 have been applied to ensure basic protection and fault protection.

Regulation number(s):

411.7.2
411.7.3

As the installer of the consumer unit has insufficient knowledge of the cable routes, the box ‘Routing of cables in prescribed zones’ should be marked ‘n/a’.

The procedure for proving dead should be by use of a proprietary test lamp or two-pole voltage detector as recommended in HSE Guidance Note GS38, Electrical test equipment for use on low voltage electrical systems. The use of multimeters, makeshift devices and non-contact voltage indicators (voltage sticks) is not advised for voltage detection as such use has caused accidents. (See also Electrical Safety First's Best Practice Guide No. 2)

The ‘Maximum disconnection time permitted by BS 7671’ column is associated with fault protection and the disconnection time to be inserted in that column should be determined in accordance with Regulation 411.3.2.2 (Table 41.1), 411.3.2.3 or 411.3.2.4, as applicable. www.beama.org.uk

Regulation number(s):

411.3.2.2
411.3.2.3
411.3.2.4

An inspection should be carried out to ascertain that the existing cable supplying the item is adequate. Tests of polarity, earth fault loop impedance and, where appropriate, correct RCD operation should, as a minimum, also be carried out. 

It is recommended that the results are recorded for the benefit of both the customer and the contractor. A suitable minor works form or works order may be used to record the details of the inspection and testing.

No. That item in the Schedule of Inspections is intended for use when that protective measure is used as the sole protective measure, that is, where a whole installation or circuit is intended to consist entirely of equipment with double insulation. In such a case, the installation or circuit would be required to be under effective supervision in normal use.

Regulation number(s):

412.1.2
Appendix 6

No. That part of the Schedule of Inspections is intended for use when a part of an installation relies specifically on that method of protection.

Regulation number(s):

Appendix 6

No. That part of the Schedule of Inspections is intended for use when a part of an installation relies specifically on that method of protection.

Regulation number(s):

Appendix 6

In principle, dead testing by the manufacturer prior to despatch is sufficient. This should be followed by live testing by the installer to fully satisfy the inspection and testing requirements of BS 7671.

It is recommended that such maintenance work be recorded on a Minor Works Certificate, job sheet, invoice or similar.

Yes. A Minor Works Certificate makes provision for all the required test results for the remedial work described, and requires a competent person to certify that the work does not impair the safety of the existing installation and that the design, construction and inspection and testing of the work complies with BS 7671.

Fitting a voltage optimisation unit might affect the existing installation in a number of ways that could have a detrimental effect on its safety, including the introduction of additional impedance (potentially affecting the automatic disconnection of circuits) and disturbance of connections possibly introducing a fault or potential fault.
 
In order to demonstrate that the safety of the installation has not been impaired, it will be necessary to perform some inspection and testing of those circuits supplied via the unit.

An Electrical Installation Certificate would be needed to record the results of this inspection and testing. It is unlikely that the necessary details could be adequately recorded on a standard Minor Electrical Installation Works Certificate.

It is necessary to carry out inspection and testing sufficient to demonstrate that the safety of the existing installation has not been impaired, including:

inspection of connections
continuity of protective conductors
insulation resistance
polarity
earth fault loop impedance.

Regulation number(s):

641.5

No.

Regulations 514.12.2 and 514.12.1 now contain certain exceptions for diagrams and documentation for domestic premises and similar.

As a minimum a certificate for initial verification, complete with the Guidance for Recipients shall be provided to the person ordering the work.

Regulation number(s):

514.12.1
514.12.2

Classification code C3.

Verification of voltage drop is not normally required unless there is considered to be a voltage drop problem.

Regulation number(s):

643.11

Yes, if:

a) The enclosed rated current in the assembly circuit (Inc) of the switch or RCCB is not greater than or equal to the sum of the rated current of all outgoing circuit OCPDs or

b) The enclosed rated current in the assembly circuit (Inc) of the switch or RCCB is not greater than or equal to upstream overload protective device rated current e.g. cut-out fuse

If conditions ‘a’ or ‘b’ are not met, then the following shall be verified:

1)            There are no signs of thermal damage at the switch / RCCB and

2)            The switch / RCCB is operating correctly;

If the answer to both checks is “yes” then a Classification Code C3 should be recorded.

If any answers are “no” then a Classification Code C2 applies.

Regulation number(s):

536.4.3.2
536.4.202

Where an inspector encounters mixed switchgear components within a consumer unit or distribution board on an existing installation, a classification code C3 (improvement recommended) may be attributed where the following criteria is assessed to confirm:

There are no signs of thermal damage to the component or associated connections
The enclosure/assembly hasn’t been modified to allow installation of the component(s)
The component is securely fitted within the enclosure/assembly and all connections, including busbar connections, are adequate ( see also BEAMA/ESF guide http://www.beama.org.uk/resourceLibrary/beama-esf-consumer-unit-connections-technical-guide.html)
Manual operation (functional test) of the component
Direction of use of toggles/switches is the same as existing devices

If any of the above criteria result in an unsatisfactory outcome a classification code C2 (potentially dangerous) would be appropriate.

It should not be assumed that mixing different models of protective devices of the same brand type in a consumer unit assembly are compatible, as products are subject to continuous development. Over time, new ranges may not necessarily be backwards compatible and therefore the same checks as detailed above should be undertaken, as well as seeking advice from the manufacturer.

The BEAMA technical bulletin provides further information http://www.beama.org.uk/asset/90FFDCC1-0E3A-4756-80BDB1BB024E09CD/

Regulation number(s):

134.1.1
510.3
511.1
512.1.5
536.4.203

No Code needs to be awarded.

Regulation number(s):

433.3.1 (iii)
434.3 (iv)

No. An Electrical Installation Condition Report should only be used for reporting on the condition of an existing electrical installation.

See also Q2.36; Q2.41 &Q2.42.

Regulation number(s):

651.4.

Type AC RCDs shall only be used to serve fixed equipment where it is known that the load current contains no DC components.

It should be noted that some appliance and equipment manufacturers now specify that a Type A, F, or B RCD is installed where fault or additional protection by RCD is required.

Where such an appliance or equipment is encountered or could foreseeably be connected and supplied via a Type AC RCD, a Classification Code C3 (Improvement recommended) would be appropriate.

However, if it is identified and confirmed that an RCD in the circuit does not operate correctly when tested, a Classification Code C2 (potentially dangerous) would be appropriate.

Where it is known that no connected loads can produce DC components that may impair the operation of the device no recommendation code is necessary.

The recently updated BEAMA RCD Handbook provides further information on the different types of RCD and their suitability for connected loads. https://www.beama.org.uk/resourceLibrary/beama-guide---rcd-selection-for-protection-of-electric-vehicle-charging-installations.html

Regulation number(s):

531.3.3
Annex A53, Figure A53.1

BS 7671 recommends that observations classified as C2 (Potentially Dangerous) are dealt with as a matter of urgency by a skilled person competent in electrical installation work.

However, for privately rented residential properties in England, landlords must complete  remedial work associated with observations classified as C2 within maximum 28 days of receiving the safety report (typically an Electrical Installation Condition Report).

Whilst no specified time for completing remedial work in rented properties exist in Scotland, Wales or Northern Ireland, a 28 day time limit would be considered ‘reasonable’.

Regulation number(s):

https://www.legislation.gov.uk/uksi/2020/312/contents/made

Where all of the following conditions are met, a classification code C3 would be appropriate:
1. The cupboard door and locking mechanism are secure and operate as intended;
2. Hinges and fixings are intact and functional;
3. There is no damage or deterioration to any exposed basic insulation; and
4. There is no foreseeable risk of damage to any basic insulation during normal use of the meter cupboard by ordinary persons.
 
Where any of the above conditions are not met, a classification code C2 would be appropriate.
 
Note 1: The purpose of a meter cupboard is to house cut-outs, energy meters, means of isolation and associated equipment.
Note 2: Where inadequacies relate to distributor equipment or intake arrangements, the person ordering the work should be advised to notify the appropriate Distribution Network Operator (DNO) or other relevant authority (e.g. the energy supplier).
 
For further guidance, please see Guidance for Service Termination Issue Reporting (issue 4.1):
https://recportal.co.uk/documents/20121/0/GUIDAN~1.pdf/9083063a-4071-7ad6-734f-ad290a582438?t=1734080521522

512.2.1
521.10.1
526.8 (noting that a meter cupboard is not to a suitable product standard to be considered an enclosure as described in 526.5).
529.3

No code is required provided the requirements of BS 7671 are met i.e., appropriate precautions to prevent unintentional or inadvertent closure are applied e.g.: located within a lockable space or lockable enclosure, padlocking, located adjacent to the associated equipment.

Regulation number(s):

462.3
464.2
537.2.4

An insulation resistance test to detect tracking (preferably at 500 V) should be applied to all circuits using the cable where green goo is thought to be present. 

If an unsatisfactory insulation resistance test result is recorded, a C2 classification code should be applied.

It is also recommended that, where possible, you visually inspect and functionally test any equipment, including protective devices, the operation of which may have been adversely affected by the green goo. If any equipment which provides protection or has a safety related function fails to operate, the inspector should record an appropriate classification code, based on the items function and purpose.   

The inspector should also consider reducing the frequency to the next periodic inspection and test, to monitor further deterioration more closely.

Regulation number(s):

643.3.2

Electrical Installation Condition Report to evaluate safe continued use.

No. Wiring systems attached to the outside of a builiding at low level are not likely to experiences premature collapse in the event of a fire. 

Although wiring systems attached to the outside of a building can eventually collapse, this will not necessarily be prematurely. 

In a situation where wiring systems are installed at low level and would not hinder evacuation and firefighting activities, no classification code would apply.

In a situation where the premature collapse of a wiring system would likely hinder evacuation and firefighting activities, a classification code C2 should apply.

521.10.202

Where premature collapse of the wiring system can hinder evacuation or firefighting activities in the event of a fire due to possible entanglement, a classification code C2 would be appropriate.

Where it is identified that a wiring system is not adequately supported, however premature collapse of the system would not hinder evacuation or firefighting activities, then no classification code needs to be awarded.

Regulation number:
521.10.202

Yes, a classification code C3 is advised.

a) If the manufacturer of the RCD provides a declaration of conformity that the device is bidirectional, this should be appended to the EICR and a classification code is not required;

or

b) if the manufacturer of the RCD does not provide a declaration of conformity, and where the device is unidirectional and has been provided:

i. for fault protection (to meet the maximum disconnection times in BS 7671), then a classification code C2 would be appropriate; or

                                                                                                                             
ii. for additional protection (but not for fault protection), then a classification code C3 would be appropriate.    

Regulation number(s):

134.1.1
411.3.2
415.1
510.3                                                                                                              
530.3.201 (Link to IET BS 7671:2018+A3:2024 download)

Note: V2X is an overarching term, covering 'vehicle-to-grid', 'vehicle-to-home/building' and 'vehicle-to-other'

A classification code C3 would be appropriate.

¹V2X is an overarching term, covering 'vehicle-to-grid', 'vehicle-to-home/building' and 'vehicle-to-other' 

²An overcurrent protective device includes:

• A miniature circuit-breaker (MCB) to BS 3871 – withdrawn and superseded by BS EN 60898:1991
• A circuit-breaker (CB) to BS EN 60898
• A moulded-case circuit-breaker (MCCB) to BS EN 60947-2
• An air circuit-breaker (ACB) to BS EN 60947-2

No, a visual inspection is all that is needed.

Note 1: It is not a requirement in BS 7671 to perform electrical tests on SPDs. Applying electrical tests to SPDs could degrade them. Also, periodic electrical testing of SPDs (after installation) is not a requirement of the SPD product standard(s) / international standard on lightning protection and not recommended by BEAMA.

Note 2: SPDs with Metal Oxide Varistors (MOVs) are equipped with a status indication ‘window’ which will indicate when the device has reached its end of life, as explained / illustrated in the manufacturer’s instructions / information. The importance of visual inspection of the SPD status indication is emphasised in the BS 7671 electrical installation condition report schedule of inspections i.e. Confirmation of indication that SPD is functional (651.4).

If any equipment connected to the circuit is of Class I construction, a C2 observation is advised.

If all equipment connected to the circuit is of Class II construction, a C3 observation is advised.

Regulation 411.3.1.1

Link to Best Practice Guide 4 Issue 7.2