I have eleven yardlights (40 watts bulbs), each light pole has an outlet and they are all controlled with two three-way switches. The one-way distance for the circuit is about 900 feet. Because of the outlets, I have them on a new GFCI breaker (Cutler Hammer). However, the GFCI breaker trips fairly regularly when I switch the lights on for no apparent reason in good weather with nothing plugged in the outlets. I have done the usual checks with my meter and can’t find a problem.
Is there some peculiar electric phenomenon taking place because of the distance that’s tripping the GFCI breaker?
Any ideas or similar experience?
lek
Replies
What is the wiring method? UF cable or wire in a raceway? metal or PVC?
It may just be capacitive coupling from the circuit conductors to the ground. I have heard GFCIs get marginal out around 500-600 feet. You might fix it with a center tapped 60-60 transformer that would balance the capacitive coupling.
G.,
It's UF cable, 10/2, with each lamp and outlet pig-tailed.
Where and how would you wire the transformer you mention?thankslek
The first thing I would do is be sure there is zero continuity between the neutral and ground ... and the hot and ground. Measure from the panel end if the run.I have not seen the transformer trick in action but I hear it works. You put it on the line side of the GFCI so it would need to be a "device" type GFCI. The theory is a center tapped 60 0 60 supply would have the same capacitive coupling on both sides so it would null.
To stay legal, you ground the center tap via the neutral in the supply.
The only troubling thing might be if you have receptacles in the run
I've done the continuity checks you mention with negative results; granted my Greenlee meter only has a 9 volt battery.
The only troubling thing might be if you have receptacles in the run
Yikes! my primary reason for the GFIB is because my wife plugs in holiday lights at each lightpole location.
lek
Arc may be onto something. You could remove the GFCI at the start of this string and just use GFCI receptacles. Lights do not require it if the wire is deep enough.
Thank you for all your help.Each pole came with its own standard non-GFI receptacle, with each one wired in parallel with each lamp, so that the receptacles
are live only when the lights are on. The GFIB only trips sometimes when the circuit is energized, i.e., the lights are turned on with nothing plugged in the receptacles; once on, the lights do not go out.Very confusing.lek
I imagine it is just the capacitive coupling of all that wire. You should be able to swap the receptacles for GFCI devices. You can go ahead and hook the light to the load side so you have full protection at each light. Dale-electric.com has the Leviton GFCI devices on sale for $7 and change. No relation, I just saw it in the catalog I got in the mail.
Actually once you get down the string a couple hundred feet you could put the rest of the string on one GFCI.
FWIW,After testing and megging the citcuit and not finding anything, I replaced the existing "commercial" grade 3-way switches controlling the lights with Pass&Seymour 'Specification" grade 20 amp switches, and so far so good.lek
Are the plugs standard duplex receptacles or GFCIs on a GFCI breaker? At 900ft, you will experiance quite a bit of voltage drop and resistance. 440W is less than 4A so it should hold. There is a formula for distance and voltage drop, but I cannot remember off hand what it is.