GFCI breakers

Anyone have experience to share in the use of GFCI breakers? Not outlets.

I'm brainstorming for our new bloom room, I'll be running a new line from the existing main breaker panel to a new subpanel (domestic USA split-phase 240V/120V). From the subpanel there will be a 240V circuit for the lights and a couple 110V circuits for accessories. Standard stuff, but I'd like to have the subpanel run off a 240V GFCI breaker in the main panel to protect everything.

Something tells me a 240V gfci breaker will trip if I use any of the 120V circuits, as current returning on the neutral is equivalent to a ground fault on the 240V lines. Are there 240V breakers that handle 120V circuits? Worst case scenario, I'll have to use a regular breaker in the main panel and put the 240V gfci breaker in the subpanel for the light circuit, and then use plain gfci outlets for the 120V circuits.

Not an electrician just want to say that first but when I ran my sub panel I didnt run a gfci breaker I just ran 2 hots a common and a ground wire and hooked the ground up to the bus bar on the main panel and independently to the box itself on the sub panel which from my understanding does the same thing as a gfci breaker and will blow the breaker if there is a ground fault occurence

they make double pole GFI breakers for hot tubs. What type panel you have? GE, Seimens? Square D Homeline or QO? Many options

I don't recommend it though. I don't use GFI in my grows, most commercial ops don't. Ghost trips ruin grows.

nathanpunk said:

Not an electrician just want to say that first but when I ran my sub panel I didnt run a gfci breaker I just ran 2 hots a common and a ground wire and hooked the ground up to the bus bar on the main panel and independently to the box itself on the sub panel which from my understanding does the same thing as a gfci breaker and will blow the breaker if there is a ground fault occurence

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A GFI breaker / receptacle will trip with a few milliamps of fault current, to pop a breaker you need to overload it and thats much more deadly.

shimbob said:

Something tells me a 240V gfci breaker will trip if I use any of the 120V circuits, as current returning on the neutral is equivalent to a ground fault on the 240V lines.

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Current NOT returning on the neutral on a 120v feed.

Standard US home, at least its not a Zinsco.
See attached pic for the glorious mess. I might just patch into the unused 30A breaker in the upper right of the second group and put the gfci breaker in the subpanel for the lights only.

I'm not convinced a 240V 2-pole split phase gfci will work if I'm running 120V circuits.

At least it's not a Federal Pacific lol

Not 100% sure but it looks like a Murray panel.

A 2 pole GFI breaker should not trip with a 120 volt load (neutral). current returning on hot legs and neutral is ok.

I still don't recommend a whole panel GFI. If one little thing like an air pump goes bad and causes a trip then everything shuts down.

I would leave the lighting without GFI, same with blowers, AC, dehumidifiers. Any pumps and stuff thats in water could have their own gfi feeds, broken down so one thing wont take a bunch of others with it.

Just run a normal subpanel feed (no green bonding screw on a subpanel only at service entry). Use GFI breakers in there for feeds that are likely to get "wet"

I found this diagram which clarifies that a 240V 2-pole gfci breaker would indeed work with 120V, as there is a spot for the neutral line from the breaker to the load. So the load would not be connected to the neutral bar in the panel but to the breaker itself and the breaker would be able to account for all combination loads. That makes sense.

Now as for whether I should, ya I think I'll pass.

Renfro said:

Not 100% sure but it looks like a Murray panel.

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You are correct, Murray.
My first home with one, I like clusters of breakers coming off another breaker.

shimbob said:

I found this diagram which clarifies that a 240V 2-pole gfci breaker would indeed work with 120V, as there is a spot for the neutral line from the breaker to the load. So the load would not be connected to the neutral bar in the panel but to the breaker itself and the breaker would be able to account for all combination loads. That makes sense.
View attachment 4386033
Now as for whether I should, ya I think I'll pass.

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If you want to use them, use them as close to the end load as possible. Putting one on the entire panel isn't nearly as effective and therefore not as safe in case of a person becoming the short circuit.

That's why they're in the wall sockets in kitchens and bathrooms, not on the main panel in the house.

ttystikk said:

Putting one on the entire panel isn't nearly as effective and therefore not as safe in case of a person becoming the short circuit.

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It's actually just as effective. The main reason for them being located in the receptacle is for easy reset. Thing is I wouldn't ever wan't a whole subpanel protected by a GFI breaker, don't want one little thing to trip the whole works and have you walking around in the dark. Using them on individual circuits is a good way to go, like for things such as submersible water pumps. Still I don't like them because a ghost trip can cause major issues if it's a flood pump on a flood and drain setup or air pumps on a DWC.

shimbob said:

I might just patch into the unused 30A breaker in the upper right of the second group and put the gfci breaker in the subpanel for the lights only.

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Be aware that the whole lower half of that panel is run off that 60 amp double pole breaker that is on the left side, third breaker down.

You're on the right track:

I know in Europe they put gfci breakers at the panel to cover entire wet rooms, so it makes sense but the risk of a ghost trip with a grow is too much.

The Gram Reaper said:

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Lmao.....

Renfro said:

It's actually just as effective. The main reason for them being located in the receptacle is for easy reset. Thing is I wouldn't ever wan't a whole subpanel protected by a GFI breaker, don't want one little thing to trip the whole works and have you walking around in the dark. Using them on individual circuits is a good way to go, like for things such as submersible water pumps. Still I don't like them because a ghost trip can cause major issues if it's a flood pump on a flood and drain setup or air pumps on a DWC.

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Then why did the master electrician I had install my 150A service tell me different? He was very clear about it, too.

I mean I've never used one for a grow but just from having them around the house I would not use one. They randomly switch off, I mean it's not real common but it seems sometimes they just switch off after months of no problem. Not just at current house either have seen at other places. If that was your exhaust fan or ac that would be a serious problem as you could bake your plants.