How to check an extension lead or cable reel
Before plugging in, inspect the cable and sockets, check shutters and load markings, and resolve doubtful earthing with a competent tester. Fully unwind reels and avoid sharing an extension between heating appliances. Factory checks can be coordinated by Cambridge China Bridge.
Inspect it while unplugged
Disconnect the extension from the wall and remove connected appliances. Inspect the entire cable, plug, socket housing and reel. Stop if you find cuts, exposed coloured wires, bent pins, cracks, loose parts, scorch marks or melted plastic. Do not tape over damage or plug it in to see whether it still works.
Check that the product and instructions identify the same manufacturer and model. A familiar plug shape does not settle approval or fuse questions: use our appliance plug guide. For a factory order, put unresolved findings in the inspection record before accepting the goods.
Look for socket shutters
With everything unplugged, look for protective shutters covering the live and neutral openings. Treat missing, broken or visibly stuck-open shutters as a reason to stop. Do not insert screwdrivers, loose pins or other objects to test them, and do not force an incompatible plug into a socket.
A government safety report describes an extension socket whose configuration allowed access to shutters and potentially live parts. Visible shutters alone do not prove safe construction. Ask a competent electrical safety tester to assess doubtful sockets, especially universal outlets advertised as accepting different plug shapes.
Verify the earth path
An earth pin and an earth opening do not prove that the protective connection runs through the cable. For an extension with earthed outlets, ask a competent tester to verify earth continuity from the plug to every socket earth contact, alongside polarity and insulation checks. A working lamp or illuminated switch cannot establish this.
Do not open moulded housings or attempt rewiring as a home check. For procurement, request results identifying the actual model and batch, then use our test report verification guide. For cable retention and strain at connections, follow our separate cord anchorage guide.
Read the total load marking
Find the extension's rated voltage and maximum total current or power on the product and in its instructions. Do not assume the plug fuse rating is the extension's load rating, or that each outlet can supply the marked total independently. If ratings are missing, illegible or contradictory, leave it unused until the supplier resolves them.
List the appliances that could run together and add their rated input currents, or their input powers when comparing with a power limit. Compare like units and use the lowest applicable limit. Do not use appliance fuse ratings as consumption figures. If only unlike units are available, ask a competent person to check the calculation.
Separate wound and unwound reel ratings
Check whether the reel gives separate load limits for cable left wound on the drum and cable fully unwound. The higher unwound rating must not be used while cable remains wound. If the label gives an unclear rating without explaining the cable condition, ask for model-specific instructions rather than guessing.
Fully unwind the reel before use and stay within its applicable rating. Lay the cable where furniture cannot crush it and keep it uncovered. Do not treat a thermal cut-out as permission to overload. If it trips, disconnect the appliances and investigate the load and cable condition before following the manufacturer's reset instructions.
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Avoid unsafe appliance combinations
Keep kettles, toasters and microwaves off the same extension. Avoid sharing an extension between heaters, irons or other heating appliances. Government home fire guidance also advises that high-powered appliances such as washing machines have a plug to themselves. Follow any appliance instruction requiring direct connection to a wall socket.
Do not plug an extension into another extension or add adaptors to gain more outlets. Use a suitable wall socket instead; ask an electrician about additional sockets if this is a recurring need. Stop using a lead that becomes unusually hot, smells burnt or shows scorching. Disconnect it if safe and have it assessed or replace it.
Frequently asked questions
Can I check socket shutters with a screwdriver?
No. Inspect visually while unplugged, without inserting objects. Missing, broken or stuck-open shutters mean stop using it. Ask a competent tester to assess doubtful construction.
Does an earth pin prove an extension is earthed?
No. Ask a competent tester to check continuity from the plug earth to every socket earth contact. An illuminated switch or a working appliance does not prove the earth path.
Can I use a cable reel partly wound?
Fully unwind it before use. Never apply the unwound load rating while cable remains wound. Missing or unclear wound and unwound instructions need resolving with the supplier.
Can a kettle and toaster share an extension lead?
Keep them off the same extension. Use suitable wall sockets and follow the appliance instructions. Empty extension outlets do not mean there is spare load capacity.