On Wednesday, April 16, 2014 10:56:18 AM UTC+1, Tim Watts wrote:
On 16/04/14 08:35, Gazz wrote:



When they put in a 220 volt appliance (tumble drier, cooker/range, big

welder, RV power, big air conditioners etc) they use both 110 volt

phases and not the neutral wire,

if the neutral is used it will be for 110 volt parts in the appliance....

the motor in the tumble drier, clock on the cooker etc.



I presume they use a double pole MCB too?



Does this mean that their back end supply is actually 6 phase?

No.

American houses are typically supplied split phase, where a single phase is centre grounded, giving two legs each at approx 120v to earth each and 240v between each other. Some do have two phases of a three phase supply giving 208v between each other (this causes problems). This is the situation at least domestically.

They also have another strange layout called high leg delta, where power is three phase delta connected, with one of the phases centre grounded, giving two legs with 120V to neutral, 240v phase to phase and one phase with 208v to neutral.

The back end is normal three phase power.

Philip