The breaker supplies a freezer and heating lamps only.

Do you understand your question, because I do not.

If the equipment is listed as 120/240, then both voltage levels are needed for the proper operation of the equipment.

240 VAC is created by taking opposite ends of the phase cycle. Each leg is supplying 120 VAC. So they are 240 volts apart from each other at their peaks.

To get the needed 120 VAC, the Neutral is inserted in the middle.

Now if you measure the peaks with a meter you would see 240 volts.

If you measure one peak to the Neutral it would be 120 volts. The same would be true for a test between the other leg and neutral.

It is not uncommon to designate a piece of equipment as needing both voltage levels. The 120 volts would be used for control of the 240 volt circuits.

Yes, a 2 Pole 120/240 Volt GFI circuit breaker can be used for two 120 volt circuits that use a shared neutral.

The equipment does not need to be 240 volt.

I'm off the mark?

I'm sorry, but I did not see anything in your post that indicates that the equipment is listed for operation on a 120 V circuit. Nor did you give us the amperage required by the equipment.

From what you put in your post, it reads as if you want to remove a conductor from a tandem circuit breaker and simply use it as a 120 volt breaker. Code violation, because you would not be using the breaker properly.

Yes a shared circuit can be used, but not with a GFCI breaker.

Give me some more accurate information and then tell me if I am off the mark.

For example, just the change in voltage will directly affect your equipment. A 240V, 30 Amp circuit will yield 7200 VA. If everything else in the circuit stays the same except the voltage you will end up with 3600 VA.

Its just not as simple as cutting the circuit in half.

Don,

The Title of the post is:

Can a Square D 2 Pole 20A 120/240V GFCI be operated on 120V only?

The remaining sentence of the post is:

The breaker supplies a freezer and heating lamps only.

Based on the info provided, seemed fairly simple to me, there is two 20 amp 120 volt circuits, and the poster wants to know if a 2 pole GFI breaker will work.

Your reading into posts more than there is.

Dear tkrussell,
Thank you for helping me out!That's exactly what I was asking.To be more exact,I have a 20A 2 pole 120/240V GFI brk.and it operates on one side(120V) only.The brk.trips intermittenly,so I thought it may needs a parallel 240V load.
Thank you!
Pogoal25

I wouldn't have freezer on a GFI.

Please call a licensed electrician!

The way a GFCI breaker works is very different from a normal breaker. To begin with as I said earlier, you use a 3 wire cable. Usually a Black (Hot), Red (Hot), White (Neutral). In operation, 120 VAC voltage is sent down each hot leg. The White is used to return the electricity back to the service. That's why it is called a circuit.

A GFCI breaker operates by monitoring the return flow from the hots across the neutral. If the amperage going out and coming back is the same, it works fine. However, if there is .006 amps difference between the two conductors the breaker trips. A GFCI breaker has connections on it for three conductors. The Black and Red hot conductors and the White Neutral. In turn, the breaker has a white Neutral that is connected to the "Neutral" bus inside of the main service panel. Its purpose is to save lives.

A multiwire cable is defined as two or more hot conductors sharing the same return neutral.

In order for a GFCI to work on a multiwire circuit, both hot circuits wolud have to be identical in design and operation. Otherwise there will always be a difference on the Neutral between one of the hots and neutral. The breaker will trip.

For goodness sake, why not just remove the 120/240 breaker and replace it with a single pole breaker for the circuit and then just blank out the open space in the panel.

Don, this is incorrect:

2 Pole GFI 120/240 Volt circuit breakers are built for multi-wire circuits.

According to your explanation, both 120 volt circuits need to be drawing the same load. You know that is not practical. I can use a multi-wire circuit for two outlets, have a load in one, and nothing in the other. The GFI CB will not trip simply because I am not using the other circuit at the same time and with the same load.

The diagram I posted is from the attached Square D Instruction Booklet for a Q220GFI circuit breaker.


To comment on Strats post, having a GFI protect a freezer is not required if in the finished space of a dwelling, however, if this freezer is located in an unfinished basement, PER CODE, it must be GFI protected.

Not saying I agree, I would hesitate putting a freezer on a GFI, simply stating what Code requires.

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48840-435-03.pdf (310.1 KB, 362 views)

TK, Thanks for the corrections.

I have the Square D Digest and did not see that breaker or diagram in it. Next time I'll put my glasses on and turn the light on.

I do stand by part of my answer that said the correct way would be to remove the 120/240 V GFCI breaker and simply replace it with a single pole breaker.