2P GFCI Breaker, No Neutral..

[Seven-Delta-FortyOne]

Say the standard hot tub panel with no 120V receptacle, just the 240V to the spa.

I run 4 wire cable to the hot tub box, so that the client can test the GFCI. It won't trip with the test button without a neutral.

But, will a 2P breaker trip without a neutral in a real life ground fault situation? Will the breaker read an imbalance between 2 hots? What if there is no 120V loads? Just 240V off the breaker?

I haven't had the opportunity to put the Lo-Z meter on it and see what happens.

 

[Little Bill]

The 2P GFCI breaker will work without a load neutral connected to them. However, they have to have their neutral connected to the neutral bus. They use the neutral to power their electronics, including the test button.

 

[Seven-Delta-FortyOne]

Ah that makes sense.

Forgot about the internal electronics on those.

 

[kwired]

Think of the GFCI as being like a clamp on ammeter.

It doesn't matter if you have single, double or three pole, with or without neutral.

If you clamp the meter around all the conductors you are intending to protect you need to read a net zero on that meter or it will trip if the net is over the 4-6 mA Class A GFCI threshold.

EGC is not a current carrying conductor of the protected circuit, and is not passed through the clamp.

Conductors not associated with the protected circuit are not passed through the clamp, or they may yield undesired trips.

The supply side neutral of the GFCI needs to be connected as the logic circuitry of the device is usually connected to the supply side neutral.

With no connected line side neutral GFCI breaker will still close the circuit and will still trip on thermal-mag functions but has no power to the logic circuitry and will not detect or trip on GFCI functions.

Some 2 pole GFCI breakers have a white pigtail but no load side neutral. Those must still have a neutral connected to allow the logic circuit to operate. Such units can not supply a circuit that has line to neutral loads though, there is no load side neutral ran through the "clamp" or CT and that will result in current being measured by the CT if connected to take some other path not through that CT.

 

[LarryFine]

Some 2 pole GFCI breakers have a white pigtail but no load side neutral. Those must still have a neutral connected to allow the logic circuit to operate. Such units can not supply a circuit that has line to neutral loads though, there is no load side neutral ran through the "clamp" or CT and that will result in current being measured by the CT if connected to take some other path not through that CT.

True dat! I had to add a sub-sub-panel to a QO residential pool sub-panel to supply a hot tub that required a neutral, because there is no 60a 2p QO breaker with a load neutral terminal.

 

[kwired]

True dat! I had to add a sub-sub-panel to a QO residential pool sub-panel to supply a hot tub that required a neutral, because there is no 60a 2p QO breaker with a load neutral terminal.

I don't know I would want too many branch circuits on a GFCI protected feeder anyway. More potential for nuisance tripping because of capacitive leakage, put GFCI on each branch. Maybe a packaged spa with two circuits and GFCI on the feeder isn't too bad though, but pool equipment panel can have much longer circuit lengths.

 

[LarryFine]

I don't know I would want too many branch circuits on a GFCI protected feeder anyway.

The feeder to the original pool panel was not GFCI-protected. It was mounted to a 4x4 post, so I mounted the new 2-space panel and GFCI breaker on the opposite side. Only the cable to the hot tub was on the new GFCI.