Single phase supply
Single phase supply is normally used for appliances which need a voltage of 220 to 250 V, for example light, fans, TV, video etc.
The voltage of single phase from supply authority is 240V.
In single phase there are three wires
· Red colour wire indicates phase wire.
· Black colour wire indicates neutral wire.
· Green colour wire indicates earth wire.
Three phase supply
The supply authority supplies three-phase supply with four wires i.e. three wires of phase and one wire of neutral.
The fifth wire of earthing is taken from the earthing pit to the consumer’s place.
The standard voltage at which the electricity board delivers power to the consumer is generally 415 V, 50Hz.
The neutral wire is usually at zero voltage.
The voltage between any two phases, in a three-phase system, is double (i.e. 440 V, the voltage between any place wire and the neutral.
The three phases are equally distributed to various rooms.
Normally, the colour code for three-phase supply should be:
· Red, yellow and blue for phases.
· Black for neutral.
· Green for earthing.
