RE: How long will we need oil15 Apr 2021 16:47
15.12
Standard UK distribution is 3 phase, and transformed down from HV to LV locally at your sub-station. Most sub transformers are set to supply 410 to 420v which allows end user at least a 400v supply as normal. Between any two of the three phases gives 400v, but this then creates an imbalance on the third, say unused phase. Most common 3 phase motors operate on three phases without the need for a neutral conductor. Neutral conductors are required when devices need 220v as a return path, so lamps etc on a control panel for example. The earthing conductor does not necessarily need a cable. It can be the sheath, or other suitable arrangement that is intrinsically protected. There are numerous earthing arrangements available..
It's 3 phase or 3 phase and neutral requiring 4 cores plus a suitable earthing arrangement. A very small amount of items such as welders can operate on 2 phases, however not popular due to the imbalance created.