I have been told that my shop has 3 phase wiring. There are 3 hot wires going in to the breaker box. The past tenant has a 3bar breaker labeled 3 phase. One of my friends said that 3phase should have a "wild leg", but all three wires are 110V each.

I'm looking to get the following compressor in 3 phase, but I want to make sure it will work with my wiring. http://www.eatoncompressor.com/catalog/item/504747/206949.htm

I think if I use all 3 hot leads it will be a 208V 3phase, is that right?

The "wild leg" you are referring to is called a Stinger Leg its usually the third phase and measures like 180v-190v ish to ground (uner 208v) and is only found where a Delta style transformer is used and tapped for 3ph, mainly in older industrial areas. Typical 3ph applications are fed from a Y style transformer, commercial and some newer industrial buildings. If you tested every leg to ground and got 120v, and then went from one leg to another and get 208v your fine. Hope that helps a little.

The "wild leg" you are referring to is called a Stinger Leg its usually the third phase and measures like 180v-190v ish to ground (uner 208v) and is only found where a Delta style transformer is used and tapped for 3ph, mainly in older industrial areas. Typical 3ph applications are fed from a Y style transformer, commercial and some newer industrial buildings. If you tested every leg to ground and got 120v, and then went from one leg to another and get 208v your fine. Hope that helps a little.


Agree (though it's usually the 'B' phase around here).

If you get the 3 phase compressor, you may have to check the taps on the motor to make sure it's set up for 'low' voltage (208 vs 480).

Operating manual should say what voltage it's delivered at.

check each leg and every one should have 120 v to them

gound wire to each leg 120 v

If you are 120 to ground on each phase you will be fine. The delta tap sytems are actually a 120/240volt three phase. The 120/208 is typically a Y-tap. If you are 120/240 three phase delta you will have a wild leg that will vary in voltage to ground, and keep this in mind if you add any single phase circuits. Never connect a single phase circuit to the wild leg. As said before, the general trade rule is to make that the "B" phase in the panel, but that is not always the case.

The bastard leg is what it's called in my area. Higher voltage though, 550volt. I have seen it in 1 building in my life and that was 15 years ago.