ECN Forum Forums General Topics of the Trade General Discussion Area Troubleshooting parking lot lights

Does anyone have a trick up their sleeve trouble shooting pole lights? I have one shorting out. The only trick I have is spitting the circuit in half. If the problem is still exists. If it goes away, it's in the second half of the circuit. The problem is I just can ohm out the lights because I'll get zero ohms no matter what. The only thing else is closing the breaker with the possibility on a still short circuit. Suggestions?

Over the years of many PLs, and many poles, and shorts, separation was the favored method. We usually split the affected circuit, or disconnected each pole at the handhole. That eliminated an underground issue. If you have concerns about energizing the circuit, you may think about putting a temporary in-line fuse on the load side of the cb.

Underground issues were attaceked by the pole to pole disconnects.

BTW, the above works well with two people minimum, and radios.

After solving whatever issue(s), I suggested in-line fuses in each pole to eliminate the multiple poles being 'out'.

It is more than likely that your short is to ground and not across the legs. How difficult would it be to isolate the ballasts/fixtures on the poles from the feed? If they are fed from underground and have an access hole at the base, I'd take everything completely apart and test each individual conductor to ground in an isolated environment.

With any luck, your underground wiring will test OK. Hook all of the supply conductors back together and fire up the circuit with no fixtures connected. If the breaker holds with nothing connected, you are in good shape.

From there, it should be a no-brainer by adding the fixtures/ballasts back to the circuit, one at a time until you find the bad one.

Unfortunately, any discharge type lighting is going to provide all kinds of strange readings to ground, so your readings of zero Ohms are fairly normal. You're going to have to do this the hard way.

It is labor-intensive, but in my mind, it is the only truly effective way to trace something like this. It is really no different than tracing an inside fault except for the weather conditions that you are obviously facing this time of year.

Sparky, I think you're on the right track.
Many years of experience have proven to me that the quickest way to find a single problem is to separate the circuit in half. Then you halve the half that showed the problem...then keep going until you have only a single item left. Doing that can identify which of 64 components is the culprit with only 6 tests and 512 with only 9.

Just keep in mind that things get out of hand quickly if you start jumping around during the testing or if you have more than 1 problem.
That's just my 2 cents worth.

The only thing I can think of to add is if you split the circuit and it holds, check the current to be sure it looks right. You could have a short to ground that only passes a few amps but still enough to trip the breaker with the full load on.

Thanx ye'all. I figured this was about the only option but it dosen't hurt to shake the ol' knowledge tree to see what falls out. This ol' dog can still learn a trick or two if they managed to get by me in my travels. I just hate closing a breaker and contactor on a short. I'd probably put a fused pig tail together and use a portable generator to find the problem child them ohm out the runs between the lights