troubleshooting yard lights

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rickl

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i need some help & ideas on troubleshooting 120 volt gfci protected yard lights, heres the situation there is 9 outside yard lights in his front yard controlled by 1 switch on porch, all have weather tight jboxs under the lights about 1 to 3 inches above grade, lights 1 thru 4 are daisy chained ( one uf cable in & one out) the fifth light has 3 cables (one from light 4, one feeds #6&#7 lights and the other feeding #8&#9 lights, all cables are 12-2 wg uf installed 7 years ago. problem started 2 weeks ago gfci tripping so i open the fifth light box & find a loose wire in box, fix the wire & lights work fine. ho calls back that night and the gfci tripped again, the next day i stopped by opened up the fifth box & remade all the connections & the lights worked, we left them on for 3 hours turning them on & off though out the 3 hours( while i did other work) that evening they tripped again. next day i installed new gfci recp & disconnect lights #8&9, gfci holds until that evening, next day i disconnect light 6-7-8-9, gfci holds until that evening, so i disconnect light 5 thru 9 and everthing worked fine for 3 days, comeback hookup lights 6 & 7, gfci holds until that evening. the thing that has be baffled is if its a ground fault why will the lights work during the day but trips in the evening, it hasn't rained for 3 weeks and the HO has not watered the front lawn. also i've checked all the lights 1-9 for loose connections or water in the boxs all look good. when the gfci trips it will continue to trip until i disconnect & reconnect the wires in box 5 then it will hold until evening. has anyone ever ran across a problem like this before. i think i have a bad cable between light 4 & 5 but my megger reads ok ( but i don't have a lot of confidence in my old used megger) & i really don't want to rip up his front yard & be wrong. any insight would be greatly appreciated
 
You checked to see if there is anything else on the GFCI circuit other then the outdoor lights?
Never go by what a homeowner tell you, when they say that is all that is on that circuit.

Megger usually shows up faults.
 
i already replaced the gfci, theres 2 entry way light & 1 receptacle on the circuit & i double checked that, with light 5 thru 9 disconnected the gfci doesn't trip.
they do have a sprinkler system but the automatic system is not working right now, they have to manually turn it on which they said they haven't did, it seems to trip around 7:00 to 9:00 pm while it still sunny & warm.
what is a good way to verify a megger is working properly, besides having your wife hold the leads while your test it.lol
 
I would disonnect all the lights and see if the gfci trips at night and then go from there. It seems there is something else that comes on at night that is creating this problem.

Another possibility is to disconnect the wires at box 5. This will disconnect the rest of the lights and see if you still have the problem. That will help isolate the issue. Eventually you can temp a wire above ground and see what happens..
 
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rickl said:
what is a good way to verify a megger is working properly, besides having your wife hold the leads while your test it.lol
Click to expand...

Sounds like a good test to me!

Put the leads together and check reading, then test with a 100 ohm res, and a 22K resistor.
 
LawnGuyLandSparky said:
If these are only lights, why is there a GFCI?
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Maybe Taking advantage of Column 4 Residential Branch Circuits Rated 120 Volts or Less with GFCI Protection and Maximum Overcurrent Protection of 20 Amperes in 300,5?

Just a guess.
 
iwire said:
Maybe Taking advantage of Column 4 Residential Branch Circuits Rated 120 Volts or Less with GFCI Protection and Maximum Overcurrent Protection of 20 Amperes in 300,5?

Just a guess.
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That would be my guess also. It's pretty typical, albeit regrettable, to find the yard light UF cables or PVC conduits just below the mulch or just below the sod. It's hardly any wonder that these things are the subject of frequent service calls.

If I was troubleshooting this, I'd get a megger that I knew to be good, and this type of problem becomes very, very easy to troubleshoot. If the OP is having troubles and doubts with his megger, time to spend 100-200 bucks a get a half decent digital. Examples of which would be the Extech 403360 or the Supco M-500. You can fuss around for a long time troubleshooting intermittantly tripping GFCI's by the guess method, or you can just megger the circuit sections out and be done with it in short order.
 
Souinds like there is something else on the circuit....hmmmmm...only trips at night......maybe photo celled?

Have you accounted for all your wire ends?


If so, my next move would be to start isolating sections of the circuit starting in the middle. Disconnect the seconf half of the circuit and see if it trips overnight. If not, you problem is in the second half. Repeat as necessary.

I hope it's not too far away :)
 
I would guess there is a lead not discovered. the only way to check that is to un-nut all boxes and do continuity on each wire to see if you have the ends of all the suspect legs identified. That mystery end may have the answer.

edit: also the neighbor's sprinkler may leech into the area and increase the conductivity of the ground.
 
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today i went back, with a borrowed megger the wire between light 4 & 5 meggers ok, so out of frustration i started opening boxs & remaking the connections with new wirenuts, at light # 3 the neutrals wirenut was rusted out so i'm hoping that will fix the problem.
thanks for all the help
 
iwire said:
Maybe Taking advantage of Column 4 Residential Branch Circuits Rated 120 Volts or Less with GFCI Protection and Maximum Overcurrent Protection of 20 Amperes in 300,5?

Just a guess.
Click to expand...

Isn't that only from 2005 code onwards? I don't remember when it came in but I did think it was less than 7 years ago which is when the OP says the wireing was put in.
 
macmikeman said:
Isn't that only from 2005 code onwards? I don't remember when it came in but I did think it was less than 7 years ago which is when the OP says the wireing was put in.
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My '96 NEC has it, and I seem to recall it in '93 (My book is long gone)
 
he mentioned that there was a neutral wirenut problem but I thought that a GFI woule only trip if it saw 5mA or more on the Grounding Cond.
 
right, thanks. I was also thinking that this would be a good case for putting some goop in the wirenuts, to prevent rusting.
 
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