Single phase GFCI protection on a 3-phase, 240V Delta panel

[goldstar]

I recently came across this situation where another electrical contractor installed a 240 volt, single phase GFCI circuit breaker for a pool motor on a 240V, 3-phase Delta breaker panel. There were 2 other pool motors attached to this panel but purely by coincidence the breakers for those pools landed on phases 1 & 3 and were working fine. When the CH-tan handle 2-pole, 20A GFCI breaker for the pool heater was installed in the panel it landed on phases 1 & 2. Needless to say, the breaker blew up. The reason - phase 1 measures 120V to ground but phase 2 measures about 200V to ground. I'm just posting this for anyone else who might run into this problem.

 

[Dennis Alwon]

It should read 240 from phase to phase. You have a high leg but the voltage between any phases should be 240v

 

[kwired]

It should read 240 from phase to phase. You have a high leg but the voltage between any phases should be 240v

But the GFCI electronics operate from one line to neutral and his case it ended up on the high leg.

That said, I kind of doubt you would find a GFCI rated for straight 240 volts, though it likely would have still "worked" had high leg been on other pole of the breaker.

 

[Dennis Alwon]

But the GFCI electronics operate from one line to neutral and his case it ended up on the high leg.

That said, I kind of doubt you would find a GFCI rated for straight 240 volts, though it likely would have still "worked" had high leg been on other pole of the breaker.

Good point-- I didn't think about gfci....

 

[CoolWill]

I don't think anyone makes a 240 volt-only GFCI breaker. They all need the neutral if only to power the internal electronics. I guess there is no market for it. One item I would like to see is a 240 volt dead face GFCI. They exist in 120 volts of course, and you can get them almost anywhere. But I think there is some room in the market for 240 volt uses as well. Leviton used to make the 8590, which is a dead face device with a toroid on the back to pass your wires through to monitor. The device itself operated on 120, but you could monitor any circuit.

WAIT!! I just found this: http://gfiwarehouse.com/gfx-220 This is pretty cool, if it is UL listed and available.

 

[goldstar]

But the GFCI electronics operate from one line to neutral and his case it ended up on the high leg.

That said, I kind of doubt you would find a GFCI rated for straight 240 volts, though it likely would have still "worked" had high leg been on other pole of the breaker.

That is correct. We went thru 3 breakers until we discovered the problem. 3 breakers x $175@ = $525 = expensive mistake