ECN Forum Forums General Topics of the Trade General Discussion Area 240V Single Pole

Update

The 416V transformers feed GE panel boards rated for 480/277. The single pole breakers are rated for 277V.

My concern here was I have never seen an air conditioning unit fed with a 240 hot and a neutral. The PTACs are all by GE so I have a call in to them.

A majority of the PTACs have been in service since 1989,so I am really wondering if I have been worried about nothing.

Wouldn't most American 240V A/C units (at least those intended for commercial use) be listed for more than 150V to ground?

They would need to be so rated for operation on a 240V corner-grounded delta supply, or if one side were connected to the high leg (208V) of a 4-wire delta.

BTW,
What does PTAC mean?

PTAC- something to the effect of "Packaged Terminal Air Conditioner", the through-the-wall units you see in a lot of motels.

I think my concern boils down to does a motor 'care' how it is getting its power as long as the voltage, phase and frequency are correct.

It looks like the answer is no, the motor does not care.

I asked the manufacturer's engineer, and he spent a couple hours going through the NEC and could find nothing wrong.

The 150 to ground issue is not a problem with 3 phase equipment in a building powered by 240 open delta.