Plugtop Wiring
A lot of problems we encounter are in the plugtop. Nowadays most plugtops are moulded on or fitted by the manufacturer by law. However there are older pieces of equipment or where plugtops are damaged in some way when you may need to fit one yourself.
This step by step guide shows you how to do it properly. If you are in any doubt don't do it, call an electrician.
Before you start you will need some tools and materials. I use a side cutter and stripper, If you don't have those you can use a "Stanley" type craft knife. Then you will need screwdrivers, usually a medium cross head and a small flat bladed one. Then of course you need a plug. Make sure it has BS1362. That's you assurance that it is up to British standards.
when you buy a plugtop invariably there are instructions on a small piece of card. Take a moment to check through these as it reminds you what colours go where and will indicate how long the wires need to be to fit properly. You don't need to be too exact with the cutting but try to get reasonably near the recommended lengths.
Start by looking how long the longest wire needs to be. In this case it's 49+6 that's 55mm. Always leave the wires a bit long. You can always cut some off but you can never cut a bit more on! Then score the outer sheath with a knife or cutters.
The flex is made up of several sections.
First there are the conductors. These are usually copper but could be another metal. For earthed appliances there will be three.
Next there are the insulators. These keep the electricity in the conductors. Nowadays they are a type of plastic material and are colour coded. Green/Yellow, for the Earth, Blue for the Neutral and Brown for the Live. Old flexes had Green for Earth, Black for Neutral and Red for Live. It is getting more and more unlikely you will see this.
Finally there is the outer sheath. This is to protect the insulators from getting damaged. Again it is usually some type of plastic material and comes in a variety of colours.
Bend the flex and the score should open and split evenly. If you score too deep you may damage the insulators. If this happens you will have to trim the whole flex and start again. Then pull off the trimmed length of the sheath and discard.
Next trim the wires to length. These usually, but not always, mean the green/yellow is longest and Brown is shortest. There are even some plugtops designed so all three wires are trimmed the same length. So check the instruction card. I use the strippers but you can use the knife. When you do be careful not to snip any of the strands of the wire. To make a good electrical connection requires all of them.
Now look inside the plugtop. It should resemble the instruction card. In most the Green/Yellow and Blue wires go left and the Brown wire goes right. They do in this one. You can see that the wires are secured by screws in the contacts. You will need to slacken these screws off before you start. At the bottom is the cord grip. In this one it is secures with two screws but some plugtops secure by friction.
Insert the cord in the cord grip and tighten the screws so it just holds in place. the cord must be secured by the sheath (The white outer section in this example). If the cord grip is gripping the coloured insulators then the plugtop needs rewiring.
Bend the wires round to their respective contacts and push the strands fully into the hole before tightening the screw to hold them in place. There should be little or no strands showing on the insulator side of the contact. You can allow the strands to poke through the contact a tiny bit.
Repeat this process for the other two wires. It is good practice to allow a little more slack in the Green/Yellow wire and less slack in the Brown wire. This is so that in the event the cord is forcefully wrenched from the plugtop then the live wire will be pulled out first (Which disconnects it) and the Earth connection will be the last to be lost.
Now select your fuse. Most loose plugtops are supplied with a 13A fuse. Very few appliances need this and we change thousands of fuses when inspecting plugtops.
Appliances up to 700W need a 3A fuse
Appliances 700W to 1000W need a 5A fuse
Appliances over 1000W need a 13A fuse.
In addition some items with motors need a higher rated fuse. They should have a 3A fuse based on their power but as a motor starts up it draws a "Spike" of electricity and will cause a 3A fuse to blow. Only if this is the case should you use a 5A fuse.
If a fuse blows or replacement fuses blow never replace with a higher rated one. Consult an electrician to find out what the fault is and get it rectified.
Insert the fuse and check all the terminal scres are tight and tighten the cord grip fully. Then put the back on the plugtop and secure it with the screw. You're finished. Well done.
