Plastic safety plug

A plastic earthed mains plug you fit to a cable yourself. For replacing a damaged plug or making up a lead to length.

Which core goes where

The colours are standardised, which is just as well, because they are the same everywhere:

• Brown is live
• Blue is neutral
• Green and yellow is earth

The earth terminal in an earthed plug sits apart and is usually marked. If you meet an old cable with different colours, do not assume you can guess it; have it checked by someone who can judge it.

Cut the earth slightly longer

This is the detail most fitting instructions give too little attention. Cut the earth core a few millimetres longer than live and neutral.

The reason is mechanical. If the lead is ever pulled hard and the strain relief gives way, the cores do not come free together but one at a time, shortest first. With a longer earth core, the earth is then the last connection to let go rather than the first. That is exactly the order you want.

Strain relief

Clamp the strain relief around the outer sheath of the cable, not around the individual cores. A strain relief gripping the cores damages the insulation and does not do the job it is there for.

If you are not confident about this, have the fitting done by someone who knows the trade. A plug costs little; a wrongly connected earth can cost a great deal.

Technical Specifications:

• Housing: plastic
• Type: earthed plug (male)
• Assembly: fitted to your own cable
• Counterpart: earthed trailing socket, plastic or rubber

Frequently asked questions

Which colour on which terminal? Brown is live, blue is neutral, green and yellow is earth.

Why cut the earth longer? So that under a hard pull the earth is the last to come free rather than the first.

Where does the strain relief grip? On the outer sheath, never on the individual cores.

Plastic or rubber? This one is plastic. The trailing socket also comes in rubber, which takes a knock better.