The guys just replaced a single phase air handler in a resturant with a new 3 phase AH.
The 3 phase panel doesn't have a seperate bond ground buss bar although the old single phase AH was grounded to the existing ground buss bar in the panel.
To look inside this old 3 phase panel you would think it's a regular single phase type because all the breakers are double pole. The only way to tell is by checking the voltage because it has no 120 volts, both hot legs are 240 to ground.
The new 3 phase Ah is supposed to have 4 wires but there is only 3 coming from the panel.
I haven't seen one of theses 3 wire - 3 phase panels since many years ago when one of my x-partners connected up a vacuum pump on the roof of a resturant with a cheater cord and found out 120 volt vacuum pump motors don't last very long on 240 volts.
Anyway, what would be the proper way to connect a case ground in this situation, just run another wire back to the panel and connect it to the ground buss?
Also, I know I'm showing my ignorance but it's been over 40 years since electrical school plus you just don't see these panels around here anymore (mostly we work with 208/120) but what is this type of 3 phase called?
