I have a 120/208 High leg delta service 4 Wire. 208v/120v/120v
The reason for the call is main breaker failed. I get there and the 1 bus bar is not being powered by the main but the other 2 are.
Remove the meter, mess with the main breaker... Its broken. Notice accumulating rust on bus bars natural, etc. Go back to customer and sell the panel upgrade and the need for outdoor rated equipment in the said building.
I test everything before and after. After I put the meter back in the high leg is reading 320v to ground, 420v to phase C, 240 to B.
I go out side and investigate and its a Delta high leg, center grounded I believe.
I can see the transformers on the pole. Tts the cheap 3phase. Standard house can with another house can for high leg.. 200amp main service on 2/0 - residential NEC rules.
I start to think its a corner grounded delta - my ground & bonding in the main is good. Even if it is a corner grounded....
How could I even change the voltage downstream.... from the meter box?
MAYBE if it was a unground system but even on a corner grounded system the grounding is up the pole. The high leg to ground reference shouldn't be changed.
MAYBE the rust and corrosion in the meter box? I replaced the load center and we are scheduled to replace the weathered meter box. But its the first time I've had to leave a customer without power; not a big deal as its a farm out building. But how?? I don't understand.