A new Amendment 3 to BS 7671 Requirements for Electrical Installations, IET Wiring Regulations, is soon to be adopted. Now is the time to have your say with the release of the draft for public comment (DPC) running from 8th May to 5th June 2024. Here we look at the changes and how it will affect you and the safety of the electrical systems you are installing. It is important to note, that this amendment, solely focuses on the issue of selection and installation of unidirectional and bidirectional devices.
What are the changes?
Two new definitions have been added to Part 2 of BS 7671 - in addition to a new regulation in Chapter 53 - as below:
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Unidirectional protective device. A protective device where it is intended the power supply is only connected to one defined set of connection terminals, and power flow is only in one direction. Note: Product standards are listed in Appendix 1 for RCCBs, RCBOs, circuit-breakers and AFDDs require these devices to be marked to indicate if they are unidirectional e.g. “in” and “out” or “line” and “load” or arrows. |
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Bidirectional protective device. A protective device where a power supply may be connected to either set of connection terminals, and power flow may be in either direction. |
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Selection and erection of equipment for protection, isolation, switching, control and monitoring shall take account of all possible directions of power flow. Where bidirectional power flow is possible, only a device suitable for bidirectional power flow shall be used. Note: Product standards as listed in Appendix 1 for RCCBs, RCBOs, circuit-breakers and AFDDS require these devices to be marked to indicate if they are unidirectional. |
What has led to these additions? Why are there only a few changes and nothing more?
The British Electrotechnical and Allied Manufacturers’ Association (BEAMA) produced a technical bulletin in August 2023 (updated March 2024) to address the correct connection of protective devices in circuits connecting items such as solar photovoltaic systems (PV) and battery storage systems.
As there are potential safety concerns, it warranted an immediate amendment.
Further information on this BEAMA bulletin be found here: BEAMA Technical Bulletin - Connection of Unidirectional and Bidirectional Protective Devices
Why is this an amendment and not a corrigendum instead?
A corrigendum is solely used to correct errors within a standard. As this is a change in the technical intent, an amendment is applicable.
How does this affect me?
When Amendment 3 is finally adopted into BS 7671, which is anticipated mid 2024,, you must ensure the correct protective devices are selected for the installations being worked upon. Electrical Safety First advises always checking with the manufacturer to establish if the devices being installed are bi-directional or unidirectional.
When installing systems such as electrical energy storage systems (EESS), electric vehicle charging equipment (EVCE) and solar PV, it is essential protective devices are correctly selected and connected according to their application due to the fact that the protective device may be rendered inoperable if not.
What about existing installations?
Electrical Safety First’s Wiring Regulation Advisory Group (WRAG); will be looking to gain industry consensus on the impact on existing installations, includingattributing suitable classification codes when conducting EICRs through the Q&A published in the wiring regulations section of the ESF website.
How do I access the document and submit any comments?
To view the document and to provide comments you must register via the .
When can I get access and what is the closing date?
The DPC will be live from 8 May with a 28-day review period for industry and individuals to comment. The closing date is 5 June at 5 pm.
Further information from the IET on the updates to the 18th Edition can be found here: Updates to 18th Edition - BS7671- IET Wiring Regulations (theiet.org)
NOTE: Due to a technical issue, the commenting section will not be available until Thursday 9th May.
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