Wiring a plug essentially involves stripping each cable back to bare wire and then connecting the live red/brown to the plugs live terminal, neutral black/blue to neutral terminal and bare or green/yellow wire to the earth terminal. Stripping wires and cables can be tricky so we will also show you some tools to get the job done easily.
Depending on the age of your wiring as stated your wire colours may differ slightly. For more information on old and new wiring colours see our project here.
Warning: To complete electrical works you must comply with Electrical Regulations – Click here for more information.
Stripping Wires and Cables
Stripping wires etc can be very easy but a great deal of care needs to be taken. As with most jobs and as we keep repeating in this book, it is much easier, and safer with the right tools. Electricians will use side cutters or cable cutters for all of the jobs you will see demonstrated below and to the side.
You will not have the ability, touch or experience to do this and a tiny little nick out of a cable, flex or wires insulation can be lethal as it will allow current to arc across wires.
Changing a plug can be every bit as dangerous as drilling through a live cable if care is not taken.
The images below show how to strip a cable for wiring into a socket or switch. The cable used for appliances is called “Flex” this is dealt with further on.
The cable shown is a 2.5mm two core and earth. First the cable is nicked through the sheath at the end. Get this nick in the middle. Pull the sheath apart a little and you will see the bare earth wire in the centre. Clamp the wire with the side cutters gently and, holding the end of the cable in your other hand, pull the wire through the insulation. This will tear quite easily.
For those with no experience its best to use pliers for this operation rather than side cutters as shown. Measure the connections you wish to make, add enough on to turn the wires over (see second image to the left) do not skimp on the length. "Stretching" cable to meet connections can mean they will pull out over time, don’t for get you house is moving all the time. It is better to have a little more than you need folded into a socket than too little.
An earth sleeve should be placed onto any bare earth wires.
Stripping flex is often more difficult than cable as it is usually more flexible because of thinner sheathing. Nicks in flex wires must be avoided.
Proprietary flex strippers can be bought at all DIY stores and these usually rely on a spring to close the cutting blade over the insulation covering. If this spring is too strong it can force the blade through the flex cover and make tiny cuts in the wire insulation beneath.
Because the blade is so sharp these nicks can go unnoticed so before connecting a plug or an appliance, twist the wire a little to make sure no nick opens up in the insulation.
Wiring a plug
Plugs are bought with a paper strip over the three pins which is, most of the time, taken straight off and thrown away. Reading this instruction card one can see that it actually gives some useful information such as the exact length the wire should be trimmed to, to enable an easy, safe connection to the plug terminal.
The live lead of your flex is coloured brown and goes to the live terminal on the plug. The connection is made at the end of the fuse in the plug. The live electricity has to pass through the fuse before it gets into the cable leading to your appliance. If anything is wrong, the fuse blows.
The neutral wire is on the left of the plug and coloured blue and the earth wire, at the top of the plug, coloured green and yellow. NOTE: It is also recommended that you make sure that the earth wire is the longest of all 3 wires and has a kink or loop in it (as you can see from the image to the right).
This is to ensure that if the cable clamp fails, the earth lead is the last wire to come loose, making sure that the electrical appliance continues to be earthed. Most plug terminals have small holes in them into which you place the stripped end of the appropriate wire.
Some plug terminals have small, brass, ring clamps which you position the cable under and screw the clamp down to fix the wire. Make sure all connections are tight including the clamp which holds the main body of the flex tight to the plug. If this is allowed to move around it will not be long before it loosens the wires in their terminals and a short circuit could occur.