ECN Forum Forums General Topics of the Trade General Discussion Area Power problem

Maybe someone has run across this before,i was called to check some plugs in a school recently,the complaint was a fried microwave oven and computers,i tested the voltage at the plugs and it was 180V between neutral and the hot wire,also 117V between neutral and ground.There were 8 wires leaving the panel in emt feeding aprox 20 plugs,6 hots 2 neutrals,service to school is 3phase 4wire.It appears only one of the circuits was affected,a red circuit,i turned the breaker off one at a time until problem cleared,it appears a black circuit was causing the problem and the voltage returned to normal on the affected circuit.Is this a possible open neutral problem? any responses are appreciated.

Sounds like maybe you have a 4 wire Delta system here!?
180-208 VAC from L-C would be found on one ungrounded conductor (typically ØB).

If not, look for open noodle situation on that branch circuit, or possibly on the Subfeed.

Scott35

A problem with the panel or transformer bonding the nutral to ground?

Just an update,turns out the problem was a neutral splice in a device box that was not twisted in the wirenut properly, intermittently under a heavy load, i believe it would arc and open circuit.