Outdoor GFI starting to trip when damp ,why?

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Old 09-19-08, 10:40 AM
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Outdoor GFI starting to trip when damp ,why?

I posted in the hot tub forum, but hope to find an answer here.


I have an outdoor hot tub were the GFI is now tripping when I turn the power on. It is OK when its dry outside. It’s been working fine up to this year, when mice made a home in the electronics box last winter, I cleaned out the box and it worked for a while. I replaced the GFI, so that’s not it.

I know GFIs work on comparing the outgoing current to the return. If they are not the same, it trips. The only other path the current could go is via the ground wire, right? (The tub has a wood frame). I measured the resistance from the red and whites (this is 240VAC) and the resistance is high. Since it occurs only when it is damp out, I assume something is breaking down, allowing current to flow to the metal frame of the control box. (where the ground wire is connected to).

Do I need to spray something on the connections to repel water? Does any one have an idea what could be causing this? I was going to take the control panel all apart again , but not sure what to check for (other then the obvious, such as exposed wires, but I checked for that last time). Is mice pee conductive. Perhaps I need to clean the board, not just remove the droppings)

If I take an air gun and blow out the control box, it starts working also. ( I assume all I was doing was drying out whatever the issue is).

Any suggestions would be helpful.
 
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Old 09-19-08, 11:13 AM
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so the GFCI trips when damp, so you go the reset it and it continues to trip ? Then you blow dry the control box (which is away from the GFCI I assume) and press reset and it stays on ? I have idea if this is the case.
 

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Old 09-19-08, 12:43 PM
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Definitely sounds like moisture in the control box is the problem. When the mice set up shop, did they chew through any insulation or vapor barriers which might be allowing moist air into the control panel?
 
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Old 09-19-08, 12:52 PM
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The solution is to keep moisture out of the control box. Seal it up.
 
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Old 09-19-08, 02:00 PM
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Mouse pee is corrosive and it should be cleaned out thoroughly. There are good non conductive cleaning sprays that work great. One is called Deoxit which is used for electronics and works well. These sprays tend to displace moisture. Deoxit is only available via mail order or on the web. You might fine some good moisture displacing and cleaning sprays in an automotive store also. You need a flushing type cleaner that is non conductive. Power OFF when you are cleaning and until it drys somewhat. You can also use a heair dryer or heat lamp to try and dry the area out and then after you have cleared the fault seal it up well.

Any path that would route the current outside of the black and white wires for that circuit could be the culprit. This includes the neutral (white) wire. If it were connected or had a path to ground, that would also trip the GFCI.

Is this GFCI outlet a standalone or does it also feed other devices downstream (are there any wires connected to the load side of the GFCI) ?
 
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Old 09-22-08, 06:51 AM
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Thanks for the replies, and yes, when I blew the box out with an air gun, it started working again. ( the GFI did not trip) Mice had chewed through 3 wires, two were bad and I had to cut the wires shorter and put new connectors on the ends ( these went to relays) one was on the transformer, and I was able to wrap electical tape around it. I will look for this Deoxit. As for the electonics box, it is made of metal and has openings all around it, so it is not moisture proof.

Sounds like I should take the board out and give it a good cleaning with some spray for cleaning electronics. Perhaps there is still bits of fiberglass insulation (which is what I found packed in there) behide the board.

And Luftzeug: I would like to hear you suggestion.

( There is another person how posted a simular question in the hot tub forum, but we had not got any real answers. suggestions)

Thanks all.
 
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Old 09-22-08, 02:07 PM
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Originally Posted by CanadianInIowa View Post
Mice had chewed through 3 wires, two were bad and I had to cut the wires shorter and put new connectors on the ends ( these went to relays) one was on the transformer, and I was able to wrap electical tape around it. I will look for this Deoxit. As for the electonics box, it is made of metal and has openings all around it, so it is not moisture proof.
First off, it's possible you missed a chew point. Punctures in insulation can be very hard to see, but once moisture gets in they still leak enough current to throw the GFCI.
Secondly, most electrical tape is not designed to be used in a harsh environment like an outdoor box, exposed to temperature changes, humidity, mouse pee Even when used appropriately, over time the cheaper tape tends to become brittle and work loose. I'd take the tape off, clean up that wire, then get some rubber splicing tape and put that on. It sticks to itself and fuses together, much more reliable for waterproofing. Then put electrical tape over it just for some physical protection.
Finally, it sounds like your wires are inside a standard electrical Jbox. These are *not* meant to be used outdoors or in any damp location. I would seriously look at replacing that box entirely. I also have to ask how the mice got in... if you have a waterproof metal box, it should be mouseproof as well.
 
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Old 09-26-08, 12:36 PM
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I found where the mice got into the box and closed it off. Also, the electronics box is that of the spas, not something added afterwards ( although I noticed new spas have plastice boxes which are sealed.) I will look over the wiring more closely for missed chew marks. It is working fine at the momement ( has not rained in a while). I'll see what happens next time it rains.

Thanks all for the help, now I can get back into hot water

Chris
 
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