The inside of a UK plug

Regular inspection of plugs and their cords is a good habit to maintain, as they can deteriorate over time. In this blog post, we explain the simple steps to check the condition of the standard square-pin plug typically found on all modern devices.

When the plug is disconnected from the socket, examine the cable:

Is the cable securely attached to both the appliance and the plug?
Is there any evidence of the cable being sliced, nicked, or otherwise damaged?
There shouldn't be any joints or repairs using insulating tape.

Next, inspect the plug:

Check for cracks or damage on the casing.
Look for indicators of overheating, such as discolouration on the casing or cable.
Check that the plug is in compliance with British Standard BS 1363 - it will be marked on the rear.
Ensure the plug cable is securely clamped into the plug and no coloured plug wires are visible.

Now remove the cover and check:

The brown (formerly red) wire is connected to live (L).
The blue (formerly black) wire is connected to neutral (N).
The green and yellow (formerly green) wire is connected to earth (E).
The cord clamp securely holds the cable and both screws are tightened.
The screws attaching the three wires to the plug are tight.
The fuse is of the appropriate size and complies with British Standard BS 1362 - consult the manufacturer's guide if unsure about which fuse to use.
The fuse clips securely into its holder, without any looseness or signs of overheating.

Finally, replace the cover securely.

How a fuse works

The fuse in a plug serves as a safety measure primarily protecting the cord rather than the appliance. It's a purposefully weak link in a circuit that will 'blow' if an electrical device or extension cord draws too much current due to overload or malfunction. The blown fuse interrupts the electricity, preventing the cord and appliance from overheating and potentially causing a fire.

Types of fuses

Generally, fuses are rated based on the power rating of the appliance. If you need to replace a fuse, after finding and fixing the reason for the fuse blowing in the first place, it's crucial to replace it with another one of the same rating. A typical UK plug usually has a 3 Amp or 13 Amp fuse.

3 Amp

Plugs for devices rated up to about 700 watts should be equipped with a 3-amp fuse (coloured red).

Examples include:

Table lamp
Television
Games console
Computer
Mixer / blender
Fridge
Freezer
Power drill
Jig saw
Soldering iron

13 Amp

Plugs for devices rated between approximately 700 watts and 3000 watts (the maximum rating for a wall socket) should have a 13-amp fuse (coloured brown).