In the US system, the hot phase is designated by a color other than white, except that bare or green is non-current carrying, or safety, ground. In a 120/240 split phase system, the most common home system, hot is black in a 120 volt circuit, and the two hots are black and red in a 240 volt circuit. Also, switched hot in a 120 volt circuit is red, but it does not really matter as the rule is "white is neutral" and "non-white is hot".
Can someone add to this, please, for the UK and other systems.
The UK's and other EU countries' nominal single-phase supply voltage is 230 V at 50 Hz. The conductors are identfied as follows in line with EU standards:
- line (not 'phase') conductor brown
- neutral conductor blue
- protective conductor green/yellow stripe
For three-phase (400/230 V) systems, the line conductors are coloured brown, black, and grey.
Prior to the EU harmonisation requirements, the UK's single-phase conductors were coloured as follows, and these will be found in all installations that pre-date the EU requirements:
- line conductor red
- neutral conductor black
- protective conductor green
For three-phase systems, the line conductors were coloured red, yellow, and blue.