Adding GFCI to existing dimmed circuit

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slamppin

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I'm working on a large aquarium that has a commercial dimming system. The cutomer requested GFCI protection be added to a circuit of lighting near the edge of a large tank. The system is not compatable with any type of GCFI dimmer module therefore, I am looking for a field installed module that would interupt the dimmed circuit. I'm assuming that the module would also need some type of constant "hot" to assure that the sensing circuit worked properly.
Has anyone heard of such a device?
 
al hildenbrand

al hildenbrand

Senior Member
Location
Minnesota
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Electrical Contractor, Electrical Consultant, Electrical Engineer
If there is a transformer between the GFCI and the aquarium lighting, a lighting ground fault will not be seen by the GFCI. . . .just a thought.

More info is needed about the system you are describing.
 
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slamppin

Member
It's just not practical in this case. There are 96 dimming circuits in the system and it's fed with an 800 amp main. The cost would be large and if there was a problem on any of the circuits, the entire system would shut down. If there is a solution, it has to be on the dimmed branch circuit side.
Thanks
 
iwire

iwire

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Location
Massachusetts
mdshunk said:
That's sorta what I was thinking, or your own zero-sequence CT and a GFP relay.
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If he needs a Class A listing that could be difficult, even the Leviton device will likely require a look by UL.
 
steve66

steve66

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Illinois
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iwire said:
Check these people out.



Bender


I think they will have what you need.
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That's amazing. I'm supprised a 400 amp circuit doesn't have 5ma of leakage current. Do you know if these class A?

I think a dimming circuit might give a standard GFCI problems. All those high freq. pulses are going to let some current couple to ground.


Steve
 
iwire

iwire

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mdshunk said:
They way I look at it, this is optional equipment. As such, if it trips at 6ma, it functionally is class A.
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That could be fine.

But we don't know what the client has in mind, if there is a purpose built / listed device I would tend to go with it.
 
mdshunk

mdshunk

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Right here.
iwire said:
That could be fine.

But we don't know what the client has in mind, if there is a purpose built / listed device I would tend to go with it.
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Me too. The one's in your link appear to have theatrical type connectors, undoubtedly meant to be used as portable protective means. That company does say they're a UL 508 shop, so they certainly could make a permanent, hardwired version.
 
D

dbuckley

Senior Member
Location
Canterbury, New Zealand
I've yet to see a GFCI type device operate happily on the load side of a dimmer.

It should theoretically be possible, but the problem is that the GFCI electronics assume that the power received by the GFCI device is full mains power, which is used to power the electronics of the GFCI.

You could ask Bender if they could make a special with seperate electronics power feeds and monitored supply which should get around the problem.

Normally, GFCIs are before the dimmers. You can get dimmers with integrated GFCIs, and you may thus be able to get an retrofit option for your dimmer. If all that fails, depending on the dimmer, you may be able to rewire the dimmer to have seperate supply for a channel (or more probably a third of the channels) and GFCI supply that.

Just what dimmers do you have...?
 
LLSolutions

LLSolutions

Senior Member
Location
Long Island, NY
I'm assuming you have some sort of ETC or Colortran dimming system, I've done several dimming systems installs and this issue has come up before, dimmed fixtures mounted in water features usually. The only viable solution I've come up with is to put all the ones I want protected into a smaller dimmer pack usually a 12 circuit and then put just that pack on a gfci breaker. I've contacted ETC about making a gfci dimmer that fits in a sensor rack but no success yet.
 
iwire

iwire

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Staff member
Location
Massachusetts
mdshunk said:
Me too. The one's in your link appear to have theatrical type connectors, undoubtedly meant to be used as portable protective means. That company does say they're a UL 508 shop, so they certainly could make a permanent, hardwired version.
Click to expand...


Yes, they mention on the web site to call them for custom work. :smile:
 
mxslick

mxslick

Senior Member
Location
SE Idaho
Great link Bob!! Thanks!!

Great link Bob!! Thanks!!

iwire said:
Check these people out.



Bender


I think they will have what you need.
Click to expand...


Indeed they will. Note that both of the LG100 models are available as "100% dimmable."

Also check out the tab "Success Stories"..these guys provided GFCI protection for the underwater lighting for "Titanic" and "Pirates.."
 
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