Extension accessories: reference notes

An extension lead gives you reach or more connection points. A surge-protected extension lead also includes components intended to limit some transient voltage surges. Neither increases the power available from the socket, and surge protection does not make overloading safe.

Reach and loading

A standard extension lead distributes the existing supply. Check the rating printed on the product and keep the total connected load within it. Do not assume every lead is rated at 13A: reels and other products can have lower limits.

Its plug fuse provides overcurrent protection for the cable. It is not a precise instant cut-off at the number printed on it, and it does not replace sensible loading or checks for damage.

• Use a lead suitable for the equipment and surroundings.
• Avoid joining extension leads together.
• Keep cables clear of doors, furniture and walkways.
• Unwind cable reels and follow the marked load limits.
• For repeated reliance on extensions, ask an electrician about additional sockets.

Surge suppression

A surge-protected strip adds transient-voltage suppression. Many designs use metal oxide varistors (MOVs); the product specification explains what protection is provided. This may be useful for sensitive electronics, but it cannot guarantee protection against every surge or lightning event.

Surge protection is different from overload protection and from an RCD. An RCD is intended to reduce the risk of electric shock in relevant fault conditions. Do not treat the terms as interchangeable.

If a protection-status light indicates a fault, follow the manufacturer’s instructions. A strip may continue supplying power after its surge protection has deteriorated. There is no single replacement interval or joule rating suitable for every product and installation.

Choosing suitable equipment

Buy from a reputable supplier, check the intended use and read the instructions. A high price, extra USB sockets or a surge-protection badge does not remove the load limit.

For workplaces, include extension leads in your equipment register. Tell the tester which contain surge-protection components so an appropriate test method can be selected. A normal PAT result is not a measurement or guarantee of remaining surge-suppression capacity.

Further guidance: Electrical Safety First extension-lead guidance.