Emergency Generator III

In domestic emergency generator work, current is generally measured in amps. Currents you will encounter in practice range from about 0.5 amps (through a lightbulb) to about 40 amps (an electric shower). Technically `amps' is short for `Ampиres', but the full name is now rarely used. The mathematical symbol for current, as it is written in calculations, is not `C' (for current) or `A' (for amps) but in fact `I'.

This is just because the symbols `C' and `A' are reserved for other things. You will occasionally come across currents measured in milliamps (`mA' for short). A milliamp is a thousandth of an amp. For example, most earth-leakage breakers used in domestic wiring trip at 30 mA, which is about one thirtieth of an amp.

To get an electrical current to flow, we need a power source, and some sort of conductor. A conductor is defined as anything that can carry a flow of electricity. In electrical practice, conductors tend to be copper wire or copper bars, usually hidden away inside plastic sleeves. The sleeves are insulators, that is, materials that prevent the flow of electricity. It is the insulator that keeps the electrical current where it belongs - inside the cable.

You can be an electrician without knowing much about electricity. It seems odd, but it's true. But if you do know the principles, you can do safe and practical work without memorizing a whole heap of regulations, because they're mostly derived from standard principles anyway. The key features of electricity are voltage, current, resistance, power, and frequency.