Quiz 1 – Basic Electrical Knowledge

While an earth path is a safety device, it can be problematic.  It is arguably better to prevent electricity leaking out of the equipment by using more insulation, rather than dealing with electricity which has already leaked out by sending it down an earth wire.

Loose connections lead to arcing which generates heat. Over time, the heat builds up and the plug will melt and burn

A 3,000W heater will draw 13 Amps from the socket, but a 10 Amp 4-way extension lead can only deliver 10 Amps without overheating.  When using a heater, it should be plugged into the wall socket, not an extension lead

The fuse is designed to protect the next thing in the circuit - the flex.  When we pass electricity through the flex during normal operation, it will get warm.  If there is an equipment fault, the flex can get too warm and set on fire.  By putting the fuse before the flex in the circuit, it will blow (and break the circuit) before the flex can get too warm.

Whoever picks up the electrical equipment to use it, is responsible for it's safety.  Although the item is officially checked on a regular basis (a 'PAT Test'), damage can occur at anytime, so it is up to the user to check it before use.

A typical BS1363 socket in the UK is expected to be able to deliver a voltage of 230V (-6%, +10%) and an alternating current of 13 Amps at a frequency 50Hz.  Some other countries use a different standard

For an electrical item to function correctly, two wires are required...one takes current to the item and another returns the current to the socket.  These wires are the live (brown) and neutral (blue).

3 Amp fuses are red and 13 Amp fuses are brown.  Non-standard plug fuses (1A, 2A, 5A, 7A and 10A) are black

Whilst we accept that electricity flows around a circuit (similar to water flowing in a pipe), in an AC circuit, the current flows down the live wire but then changes direction and flows back down the neutral. This change of direction - alternating between the live and neutral - happens 50 times a second (50Hz)

The correct wiring of a BS1363 plug is:

• Live (brown) to the right
• Neutral (Blue) to the left
• Earth (green/yellow) to the top

Don't forget, a plug needs a cord-grip to secure the flex to the plug.  One of the answer images has this vital part missing, so the plug is not acceptable, even though the wires might be in the correct positions.