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Extension leads, cable reels and block adaptors

Extension leads, cable reels and block adaptors usage and safety

It is common practice to increase the number of appliances you can plug into a wall socket. But just because you can plug in several devices does not mean it is always safe to do so.  

Extension leads are rated at 13A apart from some older versions that may be rated 10A.

Cable reels are rated according to the size of cable fitted and must be unwound to achieve their current rating. The rating should be clearly marked on the extension lead or cable reel.

Cable reels should be fitted with a thermal cut-out. If it’s not clearly marked, or if your reel doesn’t have a thermal cut-out, don’t use it.

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Check for these danger signs

  • A smell of hot plastic or burning near an appliance or socket. 

  • Sparks or smoke coming from a plug or appliance. 

  • Blackness or scorch marks around a socket or plug, or on an appliance. 

  • Damaged or frayed cables.

  • Coloured wire inside the cables showing at the plug or anywhere else. 

  • Melted plastic on appliance casings or leads. 

  • Fuses that blow or circuit-breakers that operate for no obvious reason. 

Buying an extension lead, cable reel, or block adaptor

  • Buy from a reputable retailer rather than a third-party seller online, as the product may not have passed all the necessary safety checks.
  • For extension leads and cable reels, make sure they are fitted with a standard UK 3-pin plug and a fuse.
  • Register your product so you can be contacted easily if there is a safety recall of your product. It’s also much easier to return a faulty item or order a repair if it’s registered.

Using an extension lead, cable reel, or block adaptor safely

  • Running a cable reel in its wound state can cause it to overheat and catch fire.
  • Don’t overload an extension lead, cable reel or block adaptor by plugging in appliances which, when added together, exceed the maximum current rating. Overloading can make the extension lead, cable reel, adaptor, or the plug in the wall socket overheat and cause a fire.
  • Our socket overload calculator helps you check if you’re likely to exceed the maximum load. And our home appliance ratings page helps you understand how much power is used by different devices.
  • Only use one socket extension device per socket. Don’t plug an extension lead into another extension lead (known as “daisy chaining”).
  • If you regularly rely on extension leads, cable reels, and adaptors, consider having additional wall sockets installed. Use a registered electrician to carry out this work.

ALWAYS

  • Buy from a reputable retailer and register your product.
  • Use just one extension lead or cable reel per wall socket.
  • Ensure cable reels are fully unwound and fitted with thermal cut-outs before use.
  • Check regularly for any danger signs such as burning smells or visible damage.

AVOID

  • Buying from a third-party seller online.
  • Plugging one extension lead into another one (daisy chaining).
  • Plugging in appliances which together exceed the maximum rating for the extension lead, cable reel, or block adaptor.
  • Relying too much on extension leads and adaptors. Add more wall sockets instead.

Stay safe with electrical products

Check plugs and sockets

Don't ignore burn marks, ‘arcing’ (buzzing or crackling) sounds, fuses blowing, circuit-breakers tripping, or if it feels hot to touch.

Unplug and contact the retailer, manufacturer, or a qualified repair technician. 

Protect with an RCD

An RCD (residual current device) in your consumer unit (fusebox) protects you from electric shocks if a product is faulty.

If you don’t have RCD protection, use an RCD plug on the socket where the product is plugged in.

Fit smoke and heat alarms

Ensure there is at least one smoke or heat alarm per floor in your property. Fit enough alarms to cover all areas where a fire could start.

Test alarms at least once a month. Replace them every ten years or when the replace by date is reached.

Selected FAQs

Answers to commonly-asked questions we receive about electrical safety.

View all our FAQs

Only use one socket extension lead per socket and never plug an extension lead into another extension lead.


It is bad practice to do this and should never be done as this presents a serious risk that the wall socket could be overloaded. Move the electrical item closer to the wall socket or first extension lead. Use our overload calculator to check if you’re exceed.

It is likely that you can but this does depend on your electrical installation - a registered electrician will be able to advise you whether it can be done - they will assess the load, circuit type and cable rating. You can find one local to you here.

There is no legal requirement to replace sockets if they are positioned on skirting boards in an older property but given that the wiring installation is likely to be old, it is advisable to get a registered electrician to carry out an inspection of the electrics. They will issue you with an Electrical Installation Condition Report (EICR) which will either confirm that the installation is safe or highlight any hazards that need to be addressed.

You can find a registered electrician local to you here.

It is recommended that periodic inspection and testing is carried out at the following times:

  • for tenanted properties, every 5 years or at each change of occupancy, whichever is sooner
  • at least every 10 years for an owner-occupied home
  • at least every 5 years for a business

The Landlords and Tenant Act 1985 requires landlords of properties with short leases to keep the electrical wiring in repair and in proper working order. We recommend landlords arrange for periodic inspection and testing to be carried out by a registered electrician at the relevant intervals shown above.

Periodic inspection and testing of the electrics should be carried out more frequently on the places and premises listed here:

  • 3 years for a caravan
  • 1 year for a swimming pool
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Has your electrical product been recalled?

Electrical products are recalled more regularly than you might think, but the response rate to a recall is often worryingly low. This means there are potentially millions of recalled electrical items still in UK homes.

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