2-Pole GFCI Breaker

[dpenbert]

I am wiring a 208V Whirpool Tub with two hot legs and one ground. Back at the panel I am using a 2-Pole GFCI Breaker. It is my understanding that I will connect the two hot legs to the breaker and connect the white pigtail to the neutral bus. This will leave the neutral connection on the breaker open. First question: is this the correct installation? Second question: could someone explain what would happen if I connected a neutral wire from the neutral connection to the neutral bus?

Thanks,

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David - St. Louis

 

[charlie b]

Re: 2-Pole GFCI Breaker

This thread had been temporarily closed. This action was taken because the wording of the question and the occupation shown in the Original Poster's profile raised a concern that this may have been a DIY situation.

In an exchange of Private Messages, the Original Poster has provided assurances that his interest in the project is that of designer, that the project is a condominium (not his own house), and that he is seeking information to assist the general foreman. Therefore, the thread is being returned to an active status. I offer an apology to the OP for the inconvenience and the delay.

 

[allenwayne]

Re: 2-Pole GFCI Breaker

Sounds like you ran a 2 wire with a grnd.Not a 3 wire with a ground.Is this the case ????

 

[dpenbert]

Re: 2-Pole GFCI Breaker

Yes, I designed for two-wire with ground because the whirpool requires 208V 1-PH. Of course it also requires a GFCI 2-pole breaker and there isn't a load neutral. I talked with the electrician again and he said the confusion came up because the prefab shop cut the wrong tail, a three-wire with ground.

 

[al hildenbrand]

Re: 2-Pole GFCI Breaker

If a neutral is run to the whirlpool, and the neutral is unused at the whirlpool (only deadended in some manner), it will have no effect on the operation of the GFCI.

The sensor in the GFCI sums all the currents on the conductors passing through it. Normally the current(s) out plus the current(s) back sum to zero. 3-5 milliamps leakage is tolerated. More than that is a ground fault and will trip the breaker.

The unused neutral, connected to the panel GFCI load neutral terminal and run to the whirlpool, will have no current in it as long as it is insulated from contact with ground.

A two pole GFCI requires a line side neutral connection to operate the electronics internal to the GFCI, regardless of whether the load side neutral is connected to a conductor.

 

[dpenbert]

Re: 2-Pole GFCI Breaker

So what would happen if that unused neutral was grounded?

 

[al hildenbrand]

Re: 2-Pole GFCI Breaker

So what would happen if that unused neutral was grounded?

Almost certainly the GFCI will see a current traveling in the neutral from the line to the load side, or vice versa, that has nothing to do with the L1 and L2 currents. When the current exceeds the 3-5 milliamp trip, the interrupter operates.

Remember, under normal conditions, L1 + L2 = 0.0 Amps. Any existing neutral current in the panel, finding this Whirlpool neutral grounded at some point on the load side of the GFCI, will "see" the grounded neutral as an additional parallel path back to the PoCo transformer.

The amount of the current flowing at the point of the Whirlpool neutral connection to ground will be a function of the dwelling load balance (or lack thereof) and the resistances of each of the unbalance current paths back to the transformer.

In short: Grounding the neutral on the load side of the GFCI is 99.999% certain to trip the GFCI.

(Note: I'm making up the five nines. . .there is a theoretical possibility the GFCI won't trip. . .practically speaking, it will trip.)

 

[jim dungar]

Re: 2-Pole GFCI Breaker

Grounding a neutral at any point other than at the source is a big NO NO, GFCI or not.

 

[dpenbert]

Re: 2-Pole GFCI Breaker

I agree, thanks for the explanation.

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David - St. Louis