Neutral requirement in 240V GFCI disconnect

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jstjohnz

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A "spa panel" with a 60A GFCI breaker is being used as a disconnect for a 240V heater. The heater is 240V only so no neutral needed. I assume (but not sure) that I need a neutral in the feeder to the spa panel for the line side neutral connection to the GFCI.

The not sure part is that if I'm not using the LOAD side GFCI neutral, do I really need to connect the line side GFCI neutral?

Assuming that I do, how do I size the spa panel feeder neutral given that it will not carry any load current? #6 seems a bit of overkill to supply a few ma to a GFCI breaker.
 
Sierrasparky

Sierrasparky

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No neutral necessary unless the manufacture requires it.
You will need to pull the neutral in the breaker panel like you said.

Can you place the GFCI in the panel feeding the spa panel
 
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ggunn

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iwire said:
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Originally Posted by mbrooke
My understanding is that GFCI breakers need a neutral in order to operate (internal 120 volt circuitry).
:thumbsup:
Click to expand...

I thought that GFCI only detected faults to ground; why would it have to have a neutral when the device it feeds doesn't use it? Wouldn't the neutral just be hanging out there with nothing connected to it?
 
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kwired

kwired

Electron manager
Location
NE Nebraska
jstjohnz said:
A "spa panel" with a 60A GFCI breaker is being used as a disconnect for a 240V heater. The heater is 240V only so no neutral needed. I assume (but not sure) that I need a neutral in the feeder to the spa panel for the line side neutral connection to the GFCI.

The not sure part is that if I'm not using the LOAD side GFCI neutral, do I really need to connect the line side GFCI neutral?

Assuming that I do, how do I size the spa panel feeder neutral given that it will not carry any load current? #6 seems a bit of overkill to supply a few ma to a GFCI breaker.
Click to expand...
Are you supplying a spa or just using a spa panel as a disconnect for this heater you gave no other details about? GFCI protection may not even be necessary depending on what you are feeding. That said I think it is common to have 60 amp GFCI breakers with no neutral - you can't supply loads that utilize the neutral with such breakers as the neutral current will throw off balance and make them trip - but that will not be a problem for a straight 240 volt load like you have either.
 
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GoldDigger

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ggunn said:
I thought that GFCI only detected faults to ground; why would it have to have a neutral when the device it feeds doesn't use it? Wouldn't the neutral just be hanging out there with nothing connected to it?
Click to expand...
The output neutral terminal of the breaker would not be used, but the input neutral pigtail would be used in combination with one of the hot leads to supply control power to the active electronic circuitry of the GFCI.
European RCDs may use only passive (relay coil) components.
 
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jstjohnz

Member
GoldDigger said:
The output neutral terminal of the breaker would not be used, but the input neutral pigtail would be used in combination with one of the hot leads to supply control power to the active electronic circuitry of the GFCI.
European RCDs may use only passive (relay coil) components.
Click to expand...

I'm speculating here, but I think it would make more sense to power the internal electronics from both hot leads, as in L1 to neutral and L2 to neutral, so that the GFCI will function if you have power on either L1 or L2. Otherwise, if the hot lead powering the breaker control circuitry opened, you could have a situation where there was still power on the other hot lead but no power to the GFCI circuitry.
 
J

jstjohnz

Member
kwired said:
Are you supplying a spa or just using a spa panel as a disconnect for this heater you gave no other details about? GFCI protection may not even be necessary depending on what you are feeding. That said I think it is common to have 60 amp GFCI breakers with no neutral - you can't supply loads that utilize the neutral with such breakers as the neutral current will throw off balance and make them trip - but that will not be a problem for a straight 240 volt load like you have either.
Click to expand...

It's an electric (resistance) heater for a pool. I don't think article 680 actually requires GFCI protection, but these heating elements do corrode and fail in a way that can put leakage current in the water, and if that happens it trips the GFCI.

240V GFCI breakers will work properly with unbalanced loads. Many spas for example have a combination of 120V and 240V loads.
 
J

jstjohnz

Member
Sierrasparky said:
No neutral necessary unless the manufacture requires it.
You will need to pull the neutral in the breaker panel like you said.

Can you place the GFCI in the panel feeding the spa panel
Click to expand...

Yes but still need a disconnect and the "spa panel" is quite a bit cheaper than a QO 60A 2-pole GFCI breaker.
 
kwired

kwired

Electron manager
Location
NE Nebraska
jstjohnz said:
I'm speculating here, but I think it would make more sense to power the internal electronics from both hot leads, as in L1 to neutral and L2 to neutral, so that the GFCI will function if you have power on either L1 or L2. Otherwise, if the hot lead powering the breaker control circuitry opened, you could have a situation where there was still power on the other hot lead but no power to the GFCI circuitry.
Click to expand...
Might make more sense, but that is not the way Square D GFCI's work, those are the only ones I have tested myself - the GFCI protection does not work without the line side neutral being connected. Though the breaker contacts will still close and let the ungrounded lines through if there is no connection to line side neutral - you just don't have GFCI protection anymore.:(

jstjohnz said:
It's an electric (resistance) heater for a pool. I don't think article 680 actually requires GFCI protection, but these heating elements do corrode and fail in a way that can put leakage current in the water, and if that happens it trips the GFCI.

240V GFCI breakers will work properly with unbalanced loads. Many spas for example have a combination of 120V and 240V loads.
Click to expand...
When I mentioned throwing off balance I wasn't referring to balancing 120 volts across a neutral, if the GFCI doesn't monitor neutral then any load side current that finds a way to neutral throws off the balance between L1 and L2 - which both need to be same current or the GFCI is going to trip.

jstjohnz said:
Yes but still need a disconnect and the "spa panel" is quite a bit cheaper than a QO 60A 2-pole GFCI breaker.
Click to expand...

Can't speak for other brands but I know QO series 60 amp GFCI is only available as a straight 240 volt unit - does not monitor a neutral conductor so you can not feed 120/240 circuits with it - but that is not a problem for your straight 240 volt heater either.
 
iwire

iwire

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Location
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jstjohnz said:
I'm speculating here, but I think it would make more sense to power the internal electronics from both hot leads, as in L1 to neutral and L2 to neutral, so that the GFCI will function if you have power on either L1 or L2. Otherwise, if the hot lead powering the breaker control circuitry opened, you could have a situation where there was still power on the other hot lead but no power to the GFCI circuitry.
Click to expand...

This way they only have to make one control board that runs on 120 VAC, not different, or more complicated electronics that behave correctly on 120, 208 or 240.
 
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