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Hi all. I am stumped.

Yesterday I did a few minor updates on a home that was wired in the 80s.

I will try to be brief.

There is a (surface mount) receptacle on an outside wall of a home for a deck area, the deck is 30 ft x 30 ft and other than 30 feet away the deck it 100% closed in and water tight, under no circumstances can any snow or rain come anywhere near the receptacle, nor do they use this receptacle to plug in any power tools or anything else for use "off" of the deck.
Out of the top of the PVC receptacle box is 1/2 inch PVC conduit up to a water proof switch that feeds four light in the deck area. Coming out of the bottom of the surface mounted PVC receptacle box there are two, 12/2 NMWU wires that feed two sheds (via under the ground) in the back yard. Each shed has one receptacle and one light. Neither are GFCI protected. So I decided to replace the receptacle on the deck with a GFCI receptacle to protect the two sheds.
The bottom line? Once the GFCI receptacle was installed, it trips. Every time.... When I disconnect the two 12/2 NMWU wires that feed the sheds it doesn't trip, The GFCI operates fine as a receptacle and as a feed for the lights, but again, hook up the two 12/2 NMWU wires for the sheds,,,,,it trips.

I have carefully inspected the visible part of the 12/2's under the deck (before they go underground) and they are fine.
I inspected the 12/2 s from the entry points in the shed to where they enter a junction box, the wires are fine. I disconnected everything from the junction box except the incoming feed and capped off the wires and after doing so, still the GFCI on the deck trips.

There must be a short or something wrong under the ground between the deck and the sheds, no?
Also. I tried connecting the 12/2 NMWU's independently, one at a time, and once each one is connected by itself, the GFCI trips. The only difference is when I connect one of them to the GFCI it trips instantly, the other trips after about 3 seconds.

I am sorry this is such a long drawn out explanation but I wanted to give as much info as I could. It has to be a fault in the 12/2 under the ground, no?

Any ideas or suggestions will be much appreciated.

P.S. Everything works fine if the deck receptacle is not a GFCI.
With the deck receptacle standard, not GFCI, I temporarily, installed a GFCI receptacle in one of the sheds, and it works fine. (just some added info)
Do not pussyfoot with outdoor electrical leakage. I have found issues like yours, and ended up finding underground splices where they just sliced the wires with wirenuts or electrical tape, and covered then back up! If these are tripping the GFCI, abandon those wires and run new cable. Your insurance company will be grateful!
 

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Just try the Megger for awhile, does the value slowly rise? Over a long distance in water cables can get a dielectric effect that may just imbalance the current enough to trip the GFCI. Maybe they are sitting in an underground pond?
 

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Hi all. I am stumped.

Yesterday I did a few minor updates on a home that was wired in the 80s.

I will try to be brief.

There is a (surface mount) receptacle on an outside wall of a home for a deck area, the deck is 30 ft x 30 ft and other than 30 feet away the deck it 100% closed in and water tight, under no circumstances can any snow or rain come anywhere near the receptacle, nor do they use this receptacle to plug in any power tools or anything else for use "off" of the deck.
Out of the top of the PVC receptacle box is 1/2 inch PVC conduit up to a water proof switch that feeds four light in the deck area. Coming out of the bottom of the surface mounted PVC receptacle box there are two, 12/2 NMWU wires that feed two sheds (via under the ground) in the back yard. Each shed has one receptacle and one light. Neither are GFCI protected. So I decided to replace the receptacle on the deck with a GFCI receptacle to protect the two sheds.
The bottom line? Once the GFCI receptacle was installed, it trips. Every time.... When I disconnect the two 12/2 NMWU wires that feed the sheds it doesn't trip, The GFCI operates fine as a receptacle and as a feed for the lights, but again, hook up the two 12/2 NMWU wires for the sheds,,,,,it trips.

I have carefully inspected the visible part of the 12/2's under the deck (before they go underground) and they are fine.
I inspected the 12/2 s from the entry points in the shed to where they enter a junction box, the wires are fine. I disconnected everything from the junction box except the incoming feed and capped off the wires and after doing so, still the GFCI on the deck trips.

There must be a short or something wrong under the ground between the deck and the sheds, no?
Also. I tried connecting the 12/2 NMWU's independently, one at a time, and once each one is connected by itself, the GFCI trips. The only difference is when I connect one of them to the GFCI it trips instantly, the other trips after about 3 seconds.

I am sorry this is such a long drawn out explanation but I wanted to give as much info as I could. It has to be a fault in the 12/2 under the ground, no?

Any ideas or suggestions will be much appreciated.

P.S. Everything works fine if the deck receptacle is not a GFCI.
With the deck receptacle standard, not GFCI, I temporarily, installed a GFCI receptacle in one of the sheds, and it works fine. (just some added info)
Need to remember what GFI or GFCI are the are a ground fault interrupter it trips very ease like dropping a radio into you tub while your in it it trips they are to protect you not the circuit very fast and very effetely . The problem is your run to the shed I'm willing to bet they are direct bury if the runs are lone enough the GFI sees it as a fault as all wire leaks electricity to the air and to ground so its seeing a GROUND FAULT as it see the resistance you need to remove the feed the shed and hardwire it from the panel or you could splice them in the box ( not recommended) but you can do that and put the GFCI out in the shed remember they are to protect you not the circuit you could put a breaker in the panel that is rated for GF and see how that works and just use regular outlets. a little more pricey but you may have the same problem the wire should have been put in conduit as this solves that problem as long as it scd 40. good luck, I have rand across this many times in my work OH PS if it considered a deck with an exit from the house it requires GFCI on the outlet covered or enclosed many states it doesn't matter. Its considered outside the house
 

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The problem is your run to the shed I'm willing to bet they are direct bury if the runs are lone enough the GFI sees it as a fault as all wire leaks electricity to the air and to ground so its seeing a GROUND FAULT as it see the resistance

:oops:
 

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There are longer runs in many houses than there are to those sheds.
I'd have to run the length of my house 5 times before that limit :oops:

Just how big are the shanty's up there ?? :p
 

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We have a few 6000ft² shacks up here. But think about it, even a mobile home is 70ft long. So a 70ft run to a shed is nothing.
 
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We have a few 6000ft² shacks up here. But think about it, even a mobile home is 70ft long. So a 70ft run to a shed is nothing.
Didn't read the whole thread. If the shed is only 70' away, that's not the issue.
Apparently, over 250' there can be enough leakage for false tripping.
 

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Didn't read the whole thread. If the shed is only 70' away, that's not the issue.
Apparently, over 250' there can be enough leakage for false tripping.
Soooo, for every 250' of cable in a house we can expect 5ma of leakage? That just doesn't sound right but who knows?
 

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I would consider it only AFTER ohming the wiring and probably would get my old crank style megger (if I can locate it).
If it’s a black Bakelite Biddle, I’m in!
 

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Hi all. I am stumped.

Yesterday I did a few minor updates on a home that was wired in the 80s.

I will try to be brief.

There is a (surface mount) receptacle on an outside wall of a home for a deck area, the deck is 30 ft x 30 ft and other than 30 feet away the deck it 100% closed in and water tight, under no circumstances can any snow or rain come anywhere near the receptacle, nor do they use this receptacle to plug in any power tools or anything else for use "off" of the deck.
Out of the top of the PVC receptacle box is 1/2 inch PVC conduit up to a water proof switch that feeds four light in the deck area. Coming out of the bottom of the surface mounted PVC receptacle box there are two, 12/2 NMWU wires that feed two sheds (via under the ground) in the back yard. Each shed has one receptacle and one light. Neither are GFCI protected. So I decided to replace the receptacle on the deck with a GFCI receptacle to protect the two sheds.
The bottom line? Once the GFCI receptacle was installed, it trips. Every time.... When I disconnect the two 12/2 NMWU wires that feed the sheds it doesn't trip, The GFCI operates fine as a receptacle and as a feed for the lights, but again, hook up the two 12/2 NMWU wires for the sheds,,,,,it trips.

I have carefully inspected the visible part of the 12/2's under the deck (before they go underground) and they are fine.
I inspected the 12/2 s from the entry points in the shed to where they enter a junction box, the wires are fine. I disconnected everything from the junction box except the incoming feed and capped off the wires and after doing so, still the GFCI on the deck trips.

There must be a short or something wrong under the ground between the deck and the sheds, no?
Also. I tried connecting the 12/2 NMWU's independently, one at a time, and once each one is connected by itself, the GFCI trips. The only difference is when I connect one of them to the GFCI it trips instantly, the other trips after about 3 seconds.

I am sorry this is such a long drawn out explanation but I wanted to give as much info as I could. It has to be a fault in the 12/2 under the ground, no?

Any ideas or suggestions will be much appreciated.

P.S. Everything works fine if the deck receptacle is not a GFCI.
With the deck receptacle standard, not GFCI, I temporarily, installed a GFCI receptacle in one of the sheds, and it works fine. (just some added info)
Just replace the underground wire already, it's actually a no brained, I would not put a bunch of gfci's wired on the line side, if you do, you're just ignoring the issue. Fix it right. Fix it once.
 
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