How does a GFCI brk function - Contractor Talk - Professional Construction and Remodeling Forum

mdcorreia · 05-27-2006, 10:33 AM

I have been instaling gfci of all types over the years. I actually don`t have a good explanation or know enough to explain how a 2 pole GFCI circuit breaker protecting a 3 wire cct operates? The neutral in the 3 wire is always carrying some unbalanced current due to each of the 2 ccts is feeding
a different set or group of devices, receptacles etc.
Actually I don`t think I ever had to install a double pole gfci brk unless it was strickly for a 240 V hot tub, pool etc..
I would appreciate a response.
Thanks
Mdcorreia

Sparky Joe · 05-27-2006, 12:48 PM

I'd imagine it just works like a regular GFI, but instead of the CT being around 1 wire it's around both hot, thus only picking up the inbalance between the two hots, then of course compares it to the neut.

Speedy Petey · 05-27-2006, 04:24 PM

Exactly. It monitors all three and compares the values. This is why we can use them for multi-wire circuits.

fridaymean · 05-27-2006, 04:26 PM

And, If it is 240v you do not use the nuetral pigtail.

Sparky Joe · 05-27-2006, 06:48 PM

Do you mean 240 with no neutral being used at the ampliance?

Speedy Petey · 05-27-2006, 07:00 PM

Quote:

Originally Posted by Sparky Joe

ampliance?

Is that how many amps a refrigerator or dishwasher draws?

Sparky Joe · 05-27-2006, 07:14 PM

Yeah I saw that too, but figured y'all would get it. the letters aren't even close together, oh well

mdcorreia · 05-27-2006, 08:06 PM

Thanks to all of you. It does make a lot of sense monitoring the 2 hots and the neutral.

While on the subject I do have another related question.
Could someone confirm this for me?

It seems that whenever I connect a hot tub (once every 2 years) it has been a 120/240 so I obviously connect the Neutral from the GFCI to the neutral terminal at the disconnect and continue with the neutral from the GFCI to the tub. However if it had been a 240V tub then I could use the spare #6 blue wire in the teck cable for it`s ground instead of running a seperate #6 bare back to the panel? I would not have to connect the neutral pigtail from the GFCI? would that be correct?
Thanks all of you and have a great week end.
MDC

Speedy Petey · 05-27-2006, 08:24 PM

Quote:

Originally Posted by mdcorreia

However if it had been a 240V tub then I could use the spare #6 blue wire in the teck cable for it`s ground instead of running a seperate #6 bare back to the panel?

Uh-oh! He's speaking Canadian. Someone needs to translate.

Seriously, I don't know if the CEC allows re-identifying blue to green. We can over a certian size (#4 and larger).

Quote:

Originally Posted by mdcorreia

I would not have to connect the neutral pigtail from the GFCI? would that be correct?

Not correct. The tail from the GFCB always has to be connected to the neutral bar, regardless if there is a load neutral or not.