Two pole gfci breaker

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480sparky said:
Not having a grounded connection to verify any line/load imbalance, it would default to a trip.
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Just done some tests to see what happens with a 50 amp 2 pole QO GFCI (with neutral).

Plug breaker onto bus, leave neutral pigtail disconnected - breaker does turn on with no load you can measure 240 volts on output lugs (with a low Z meter so there is current above 4-6 mA flowing when testing).

Pressing test button does nothing.

Move one low Z meter test lead to the neutral bus in the panel so there is "fault current" flowing and the breaker trips, even though the neutral to the breaker was not connected. (this surprised me a little)

Thought I might read some voltage between the unterminated neutral pigtail and the neutral bus, but did not. (pretty sure I still had meter on low Z setting)

Connected neutral pigtail to neutral bus and things worked as they should - test button did trip the breaker as well.

Can't tell you if other brands of GFCI's will do the same, guessing Homeline does do the same though.
 
480sparky said:
Not having a grounded connection to verify any line/load imbalance, it would default to a trip.
Click to expand...
A common misconception is that the GFCI needs a neutral for some reason other than control power.
If the load does not use a neutral, then any current imbalance between hot wires must be a ground fault and will be detected IF the electronics have power.

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GoldDigger said:
A common misconception is that the GFCI needs a neutral for some reason other than control power.
If the load does not use a neutral, then any current imbalance between hot wires must be a ground fault and will be detected IF the electronics have power.

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Click to expand...
See my previous post, I thought the same thing, but still tripped a QO GFCI with an imbalance current when the neutral pigtail was not connected, I thought it wouldn't trip before I attempted it. the test button did not trip it when neutral was disconnected though.
 
480sparky said:
So............ the pigtail needs to be connected if one requires GFCI protection.
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From the ones I've seen over the years, generally yes.

The Neutral pigtail activates the GFI portion of the breaker and will detect a ground fault whether there is a return neutral conductor terminated to the Neutral lug on the breaker from the load itself or not.

For instance a 240v 3 wire hot tub, there is no return neutral from the tub to the GFI Breaker, only 2 hots and an EGC, but as long as the Neutral pigtail is terminated
the GFI Breaker will monitor the phase to phase current on the (2) CCC's from the tub and will trip if there is any imbalance.

However,

Not having a grounded connection (Pigtail terminated to the Neutral Bar) generally does not cause the breaker to trip immediately when you turn it on.

At least not any that I've ever checked that is.

Not sure why K-wires Test tripped without the pigtail connected with an imbalanced load when the test button would not.

The sensing portion of the new GFI's may have changed somewhat over the years.

Not sure.

JAP>
 
kwired said:
See my previous post, I thought the same thing, but still tripped a QO GFCI with an imbalance current when the neutral pigtail was not connected, I thought it wouldn't trip before I attempted it. the test button did not trip it when neutral was disconnected though.
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My guess is that they wised up and are powering the electronics from 240. The test current apparently still bypasses from one line to neutral.

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Why don't they just make 2p GFI Breakers with no pigtail at all then?
Maybe something coming.

JAP>
 
jap said:
Why don't they just make 2p GFI Breakers with no pigtail at all then?
Maybe something coming.

JAP>
Click to expand...
Because they would then be useless for MWBCs or any 120/240 circuit containing even one line to neutral load?

If the demand exists for GFCI for purely 240V loads, then someone may start making them. But initial cost may be higher than the ones with pigtail or neutral bus connection.

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jap said:
Why don't they just make 2p GFI Breakers with no pigtail at all then?
Maybe something coming.

JAP>
Click to expand...
QO 60 amp GFCI doesn't have a neutral. You can not use it for anything with 120 volt loads either though.

Then there is "plug on neutral" breakers in both QO and Homeline series that still have a neutral but no "neutral pigtail".
 
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