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I'm having trouble with an outside pole-mounted light fixture on a circuit with an outside GFCI plug. Last summer I built an interlock entrance to the house and while excavating for the crushed stone base (I wanted to make sure it was solid so I went 18" below grade) I unearthed pvc conduit running from the house to the outside lamp. The problem was, the conduit was cracked at one point, exposing the cable inside. I was afraid that left like this, the compaction of the crushed stone could possibly cut the insulation, so I decided to fix the conduit. I cut the wire so as to install a pvc junction box for wet locations and spliced the wires in the box. Now, almost one year later, the GFCI on the circuit trips. Today, I tried to diagnose the problem. I first disconnected the run to the lamp from the GFCI. When I turned the power back on, I reset the GFCI and all was good. This lead me to believe that the fault is somewhere between the connection to the outlet and the lamp itself. Next, I disconnected the photovoltaic cell from the lamp run and reconnected the run to the GFCI. It tripped again when turning on the power. Finally, I took out the lamp itself. When I turned the breaker back on, another trip occurred. Thus, I concluded that there's a short somewhere in the wire between the GFCI and lamp. I took an ohm-meter and measured resistance between hot-neutral, hot-ground, and neutral-ground at both ends of the wire. The meter showed no continuity. This left me confused. Do you guys have any ideas on what's going on? The last thing I want to do, obviously, is take apart the interlock and excavate the crushed stone and redo the conduit entirely. I definitely don't want to do this now because I don't even have conclusive evidence that it's the problem.
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Jun 25, 2009 17:32
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| # ¿ May 2, 2024 12:19 |
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babyeatingpsychopath posted:Your conduit and splice box are full of water. Underground conduit always gets full of water. Dig up the junction box, install some direct burial splices, rebury the box. You could also dig up the box, drain and dry it, fill all conduit entries with approved potting compound (RTV, silicone, etc), then close it back up. Ideally, you'd dig up the box, repair the pipe, and repull the wire to have a continuous run. Insulation doesn't care AT ALL about water, but splices do. You're right. I rechecked the run from the outlet to the lamp with a multimeter set to 2000k ohm and found that hot shorts to ground. I guess I'm going to have to dig the entire bastard up and just do what I should have done originally - pull one, uninterrupted run of UF from GFCI to lamp (can't do this without digging because of the marrettes - I already tried). Hell, this way if something happens in the future, I don't have to do any digging, just pull another wire through the conduit. Oh well, I guess this gives me an excuse to modify the design of the entry steps, which, once I finished the project, didn't like.
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Jun 27, 2009 14:27
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