Cable Forum - View Single Post

altis · 03-08-2003, 22:52

For at least ten years, UK mains has been nominally 230VAC. However, the tolerances are asymetric. I can't remember the actual numbers but it's something like +10% and -6%. If you stick a meter in a socket it will often measure 240V. The nominal voltage has been changed as part of harmonisation with Europe - which is on 220V.

The phase wire carries the current from the substation. The neutral carries it back again. Because the neutral wire has a small resistance, the potential at the appliance not be the same as earth. Remember Ohm's Law (V = IR). This is why we need an extra earth wire.

03-08-2003, 22:52	#27
altis Inactive Join Date: Jun 2003 Location: Warrington ntl:81304 Altitude: 12m (and falling) Posts: 4,499	For at least ten years, UK mains has been nominally 230VAC. However, the tolerances are asymetric. I can't remember the actual numbers but it's something like +10% and -6%. If you stick a meter in a socket it will often measure 240V. The nominal voltage has been changed as part of harmonisation with Europe - which is on 220V. The phase wire carries the current from the substation. The neutral carries it back again. Because the neutral wire has a small resistance, the potential at the appliance not be the same as earth. Remember Ohm's Law (V = IR). This is why we need an extra earth wire.