GFCI moisture protection

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sparrott4

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I'm spawning a new thread from my previous thread to deal specifically with how to prevent moisture intrusion into an outdoor GFCI receptacle.

I spoke with an electrical engineer who believes that nuisance tripping of outdoor GFCI receptacles is usually due to moisture that collects on the underside of plugs inserted into GFCI's. A couple questions about this.

1. Even weatherproof in-use GFCI housings may be subject to moisture intrusion from imperfect seals or condensation. Does anyone know of a grease, lubricant or other compound that can be applied to plugs before they are inserted into the receptacle. This would serve to prevent moisture from setting up a current conduction.

2. Does anyone seal waterproof enclosures with silicone caulk, plastic bags, etc?

3. A couple people posted their favorite weatherproof GFCI's - Leviton and Thomas & Betts Red Dot series. Any other suggestions? Keep in mind that the plugs need at least 3 1/2" space out from the outlets.

Thanks!
 
How many of these GFCIs are tripping? How frequently? What's the condition of the wiring connected to them?

If you're getting a lot of repeated trips, I think the problem is something other than simple "moisture on the plug." I've seen a lot of GFCIs operate in very humid and wet conditions without nuisance tripping. We have GFCI receptacles in hydroelectric dams where water actually trickles out of the outlet boxes, and the GFCIs don't nuisance trip and will test properly.

Personally, I'd keep trouble-shooting this. You may also have a batch of ultra-sensitive GFCIs. I've seen bad ones trip at <3mA.

-John
 
The contractor complaining about the GFCI tripping claims that this has happened on several jobs. The GFCI's have been replaced in each case but the problems persist. I don't know about the wiring quality. The tripping always seems to be intermitant.
 
The only way I know of to prevent moisture invasion is heat. Try putting a trouble light or some other source of heat under the GFCI. Should not require much heat, just keep the GFCI a couple degrees warmer than the ambient.
 
I have another idea to keep the GFCI warm, but I do not know if it would violate any code rules. I will count on other members here to comment on that aspect. Size a 5 or 10 watt resistor to dissipate 2 or 3 watts of energy ( heat ) placing it inside the enclosure with the GFCI. Strip wire from another conductor to insulate the resistor's leads. Power it from the load side of the GFCI. Use a resistor with a suitable voltage rating, not a printed circuit board resistor from Radio Shack.
 
Sparrot,

""2. Does anyone seal waterproof enclosures with silicone caulk, plastic bags, etc?""

Yes
Silicone, plastic bags, marine duct seal.
It is a PIA this nuisance tripping.
I've put marine seal around the prongs of a plug prior to insertion,
and then black taped the hole thing, to keep a customers cord from picking up yard water. I aim to make it work!
:)
 
SG-1 said:
I have another idea to keep the GFCI warm, but I do not know if it would violate any code rules. I will count on other members here to comment on that aspect. Size a 5 or 10 watt resistor to dissipate 2 or 3 watts of energy ( heat ) placing it inside the enclosure with the GFCI. Strip wire from another conductor to insulate the resistor's leads. Power it from the load side of the GFCI. Use a resistor with a suitable voltage rating, not a printed circuit board resistor from Radio Shack.
Click to expand...

SG-1,

So, R=E^2/P.
Resistance is 120V squared, divided by 2 Watts.
which is aprox. 700 Ohms, in a 5 Watt package, at 3/8 inch on a side. It might fit in a 2x3 switch box, behind the GFCI. I think you are manufacturing a heater device,
and should have it 'listed' and maybe insured.

Voltage rating would be a consideration only if you are dealing with voltage high enough to arc the length of the resistor. So, 5,000 V is too much for a 1/4 Watt resistor of half inch resistor, which would burn anyway.
But a 5 Watt ceramic is 2 inches long.

I wonder what 2 Watts, placed directly on the side of a plastic switch box,
would do the blue plastic? Might melt a hole!

But, I like the idea.
Never let practical considerations
get in the way of thinking up new ideas!
:)
 
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