Tag Archives: plug

Plug wiring colour scheme

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UK plugs use brown insulation for the live wire, blue insulation for the neutral wire and green with yellow stripes insulation for the earth wire.

But why this particular combination of colours? The answer is deceptively simple: there is no type of colour blindness that will result in these wires becoming confused.

Above: how a UK plug looks to someone who is red-green colourblind.

Above: how a UK plug looks to someone who is blue-yellow colourblind.

One of the lesser-known safety features of a UK plug is the extra distance that the neutral wire has to travel when compared to the live wire. If someone pulls on the mains cable the live wire will disconnect first, making the plug safer.

Under the IEC 60446 standard only black, brown, red, orange, yellow, green, blue, violet, grey, white, pink and turquoise are acceptable colours for labelling wires. Countries must choose an appropriate selection of colours that eliminates the possibility of confusion.

IEC 60446 colours. From top to bottom: normal vision, deuteranopic vision, tritanopic vision.

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How to make an extension cord

Sometimes the cable that comes with the device just isn’t quite long enough. In most situations you can just make do, but what if you don’t want to? Making a short extension cord isn’t really difficult at all; all the parts shown below are available from any good hardware/electrical shop.

Wiring the plug is well-covered elsewhere on the web so I’ll only comment on wiring up the pins themselves: the easiest way is to insert the stripped wire all the way through until the insulation reaches the screw holding the wire down, and then snip off any remaining copper.

First you need to remove the socket cover.

Make sure that you take the cover and slide it all the way along the wire before you start wiring, otherwise you’ll find yourself wasting time taking it apart and putting it back together again.

Once the cover is off it’s simply a matter of wiring up the pins correctly – blue to neutral (labelled ‘N’), brown to live and green/yellow to the Earth.

Once that’s done simply slide the cover back along the wire and screw everything into place.