How to Wire a UK Plug
UK plugs have three pins - live, neutral and earth.
Many are also fused to give you added safety in the event of electrical appliance failure.
If you need to know how to wire a UK plug, read on.
Assuming you have bought a new plug to replace a damaged or burnt out one, you will find that nearly all new plugs come with instructions written on the back of a standard plug, on a paper insert that is removeable.
While wiring the plug is simple, not everyone knows to look at the amperes of the fuse.
Getting a plug with the right size of fuse for your appliance is just as important as correctly wiring it.
If you connect a heavy duty appliance to a fuse that is too light, your appliance will not work and will immediately blow the fuse, meaning you will have to replace it with a heavier fuse.
Tools you will need to wire a UK plug
- A pair of pliers or wire-cutters to cut electrical wire
- A small flat-headed screw-driver.
- A Phillips screwdriver.
- In the absence of any of the above tools, a small knife will do instead so long as no wire cutting is necessary.
How to wire a plug
With the Phillips screwdriver, undo the centre screw and set aside.
Loosen off both of the bottom screws to release the cable.
Remove the cover off the plug.
If your appliance has three wires they will be colour-coded.
Neutral - The blue or black wire goes to the pin bottom left as you look at the open plug.
Live - The live wire is always brown or red, and goes to the pin on the right-hand side, where the fuse is.
Earth - Not all appliances are earthed, but if it is, the wire will be green or green and yellow. This wire goes to the pin at the top of the plug.
- Use the small flat-headed screwdriver to unwind the screws at the top of each terminal.
- Use the pliers or a knife to cut the plastic insulation away from the top quarter-inch of the wire, if not already exposed.
- Twist the strands of copper wire into a point, so that they all stay together.
- Insert the copper tip of each wire into the hole at the bottom of the terminal post. When you tighten up the screw again, it should hold the wire in place.
- The neutral wire goes to the neutral terminal, the earth to the earth and the live to the live as described above.
- In some designs of plugs, it is difficult to reach the live terminal because the fuse is in the way. Simply slip it off its holder, and return it when the wire is firmly in place.
- Replace the cover and the screws.
- Make sure the screws holding the cable grip are securely home. This will prevent unnecessary movement of the cable which can loosen off the terminal wiring over a period of time.
While the neutral and live wires should be as near as an exact fit as you can make it, it is a good idea to leave some extra length on the earth wire.
This should mean that in event of accident (for example if you drop the appliance while it is still connected to the electrical outlet), this wire will be the last to be released from the plug.
Video on how to wire a UK plug
Connecting a 2-wire appliance to a 3-pin plug
If your appliance only comes with two wires, then one will be live and the other neutral, and should be wired as normal, or as shown in this photo.
Not all appliances are, or need to be, earthed.
The device in this case was a plastic-coated radio.
Are Earth wires necessary?
The earth wire ensures any accidental passage of live electricity through the metallic casing of any appliance goes to earth, and not into the body of any person touching the appliance, thus avoiding electric shock.
This function is called 'ground' in the US, but 'earth' in the UK
Earth wires are only really necessary on electrical goods that have an all-metal casing. Plastic is not a good conductor of electricity.
The earth pin on a UK plug is longer than the other two. This function is to allow this pin to break the spring-loaded guard inside a socket that is designed to prevent objects being inserted into the live or neutral terminals.
You cannot insert a two-pin appliance into a 3-pin wall socket in the UK for safety reasons.
Special two pin sockets are available for electric shavers which normally come already fitted with 2 pin plugs, or adapters are available to use.
What size fuse should I use?
In the UK, all electrical appliances come already factory fitted with a plug, and a fuse suitable for the expected electrical load.
Only two are in use - 3 Amp and 13 Amp. You can also buy 5 Amp fuses but will not receive an electrical appliance with one already fitted.
Basically, anything that uses greater than 700w needs a 13A fuse, and light appliances need a 3A fuse.
When you need to replace a plug, you can buy one fitted with either a 3A or 13A fuse, and it important to get this right.
The fuse is the circuit-breaker between your appliance and the live electricity carried by the mains.
If you fit a 13A fuse in a small electrical appliance that only needs a 3A, in event of a power surge your device will get damaged as too much electricity will pass through.
It is also a fire risk, as your appliance could overheat and burst into flames before the fuse kicks in and breaks the circuit.
Small appliances that require a 3A fuse
- videos, satellite boxes, DVD players
- refrigerators and freezers
- small kitchen appliances - mixers, blenders, ice-cream makers
- power tools - electric drills, saws, jigsaws etc
- lamps and small lighting
- vacuum cleaners
Heavy-duty appliances that require a 13A fuse
- Washing machines
- tumble dryers
- microwave ovens
- curling tongs
- electric heaters
and any heavy domestic device that creates heat.
Getting the fuse wrong is easily done. I thought my hair-dryer was broken after wiring it to a 3A plug, but of course the current was too great for it. Instead of completely re-wiring the plug, you can simply change the fuse.
This article is written specifically on to how to wire a UK plug and should not be used for any other country unless the type of wiring is identical.