ECN Forum Forums General Topics of the Trade General Discussion Area Underground fault

Need help in troubleshooting the following: Outdoor circuit from GCI receptacle to light switch (for pool light), on to two receptacles, all wiring between each is buried 12/2 w/g UF. When powered up, GFCI trips but after 15 sec to 5 minutes. I have isolated the fault to the wires between the switch and receptacle, but am perplexed as to why the delay in tripping the GFCI. Would a nick in the neutral insulation be causing this?

That, or leakage from the lights. The delay could, in part, be related to temperatuse changes...or a 'borderline' fault that is very close to the trip level of the GFI.

I think it's time to get a megger and do some serious testing.

It's not the lights. It will still trip with them out of the circuit. The suspect length of wire will trip the GFCI with nothing connected to the end. A nick is what I suspect, but am surprised by the variable times on the GFCI tripping.

Megger cable first, 500 Vdc

Ph to Neutral.
Ph to Earth
Neutr to Earth
and from each individual core to ground, to establish if it's external damage

Have both ends disconnected,

Is it a screened cable?

or 2 or 3 core with no screen.

then fault locaion is easy.

POPIE for an earth fault or Thumper for internal cable fault.

A TDR would also be handy.

A good one is pricy. But they jump through these kinds of challenges.

If this is under soil and not concrete, try this. Go to your nearest Big Orange store at about 7:00 am. Locate a couple of fellows hanging around the front area who dress and look like they are from outside your county line. I promise they will work at an affordable rate. Have them re-dig the thing and this time you can put in pvc and upgrade the whole shebang for the customer. Make sure though when you hire your new helpers, that you follow all state and federal hiring laws and also make sure that you have the proper workmans comp and other required insurance in place. This will probably be a less costly solution than trying to TDR the wire and locate a nick, unless you have ready access to the equipment.

Mac..your profile says you're based in Hawaii. I've been to Hawaii; quite the cross-roads where Occident meets Orient.
Just what does "from across the county line" look like there?

Is Home Depot offering casual labour a new thing in the US?

Here where I am in Canada (Winnipeg MB) they don't do it. I can't even find service staff in the store (except at the checkout register) at that time of the morning.

Merly pointing out a time tested value packed way to get the fix in without resorting to a lot of test equippment and head scratching. Some days I can see across the county line from my window, but it is 27 miles across deep ocean so I can't quite see what they look like over there.

From what I understand picking up "casual labor" in London = finding a desperate American looking to work for the summer.
Guess it's the same world 'round?

Anyway back to the TOPIC....

Try the circuit (for testing purposes only) without the GFI and test for current.

No current.... Try a new GFI.

If all else fails, cut the power, grab the wire and aggressively rip it out of the ground. This will loosen the soil plenty for its replacement. (Without the casual labor)