PAT testing extension leads and RCDs
Extension leads are their own items
An extension lead is not just a cable — it is tested as portable equipment in its own right, usually as Class I. That means earth continuity, insulation resistance, wiring polarity, and a visual inspection of every socket along the length. The lead supplying a pass-fail kettle can itself fail while the kettle passes.
This catches people out in offices (“we only tested the computers”), holiday lets (guests daisy-chain adapters behind sofas), and HMO kitchens where a single lead serves multiple appliances. If it is plugged in and left for use, it belongs on the register.
Why leads fail so often
They are trodden on, coiled while hot, pulled by the flex instead of the plug, overloaded, and left permanently under tension. Failed grips expose conductors; crushed sockets lose earth contact; DIY rewires swap live and neutral. These are exactly the hazards formal PAT is designed to catch.
Our most common PAT failures guide lists extension leads and multi-way adaptors at the top for good reason. Replacing a £12 lead is cheap; an unchecked failed lead is not.
RCD extension leads and adaptors
An RCD (residual current device) extension or adaptor adds shock protection — typically tripping at 30 mA or less for portable devices. The IET Code of Practice expects the RCD to operate within defined trip times when tested with a suitable instrument.
Testing includes the usual lead checks plus confirmation that the RCD trips correctly. Outdoor use, construction, and event setups often rely on RCD protection; a lead with a stuck RCD gives false confidence. Include RCD-equipped leads on the same schedule as other leads unless your risk assessment says otherwise.
What to include on your register
Every extension lead and multi-way adaptor in regular use — desk banks, server cupboards, holiday-let TV corners, cleaning cupboards. Label each with a unique ID. Note whether it is RCD-protected. Retest at the shorter interval if the lead serves high-risk equipment.
Discourage daisy-chaining (plugging one lead into another). It is a common guest and staff habit and increases overload and earth path failure risk. A short policy note for staff or a line in your guest handbook costs nothing.
Practical tips before your visit
Gather loose leads from drawers and cupboards — untested spares often migrate back into service. Replace leads with cracked sockets or heat damage before the visit; they will fail anyway. For portfolios, photograph where leads live if access on test day might be tight.
Fixed prices from £89 across Devon and Cornwall include testing and labelling every item we can access — leads included. See our pricing guide for band sizes.
Quick answers
Do I need to test a lead that is permanently plugged in behind furniture?
If it is part of how the room is used and not considered fixed wiring, yes — it should be on your PAT register and tested at appropriate intervals.
My RCD test button works — is that enough?
The manual test button is useful for monthly user checks, but formal PAT includes measured trip time where the Code of Practice requires it — not just “it clicked once”.
Are multi-way adaptors banned?
Not banned, but they are high-risk when overloaded or damaged. Many organisations limit them or require fused models. Test them, label them, or remove them from service.
Relevant services & areas
Booking or compliance questions for your premises? These pages go deeper on what we test locally.
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