The UK has plugs, well every country has plugs but the ones in the UK have three pins.

The pins are made out of brass since it is a__ good conductor__ of electricity and won’t rust.

The outside of the plug is made out of plastic since plastic is a good insulator and prevents electric shocks.

Within the plug there are a number of different components, let’s discuss each one with its use.

Plugs, figure 1


  • Live wire - brown - this carries the alternating potential difference from the supply.
  • Neutral wire - blue - this completes the circuit, taking the current back to the source.
  • Earth wire - green and yellow stripes - this is a safety wire to stop the appliance becoming live. If there is an electrical fault the earth wire will carry the current into the earth and prevents the current from entering a human person and harming them.


The fuse is also a safety device. Inside a fuse is a small thin wire. If the current gets to high, it will heat up the wire which will cause it to melt __and __break the circuit. In the event of this happening, the fuse has to be replaced before the plug will work again.

Plugs, figure 1


There is a danger if the live __and __earth wire are connected since there is a large potential difference between them (230V in the UK). This can cause a spark of electric shock is someone is too close.

Power Ratings

Every appliance comes with a power rating in Watts. Recall that power is the rate of energy transfer over time. This means that the higher the rating the more energy is transferred.

What colour is the live wire?
What colour is the neutral wire
What colour is the earth wire?
Your answer should include: green / yellow
What is the frequency of the UK mains electricity supply?
Your answer should include: 50Hz / 50 Hz
Why are the plug pins made out of brass?
Your answer should include: good conductor / does not rust /