Solve This Service Call : Chapter 2 - Electrician Talk - Professional Electrical Contractors Forum

480sparky · 07-15-2009, 07:42 PM

OK, here's another one for ya. Customer has a circuit breaker in his barn (on a farm) that won't reset. Here's the panel:

Other symptoms: Exterior HID doesn't work, and some inside lights won't work either.

So given the situation and known facts, what would your next step be?

(Let's ignore the shopping list of violations for a moment, and concentrate on getting power back on!)

Please note: I already know what the problem is. It has been located and corrected. The reason all the breakers are closed in the photo is because I HAVE FOUND THE PROBLEM.

I am not 'fishing' for a solution. This is simply an exercise to help those interested in honing their troubleshooting skills.

NolaTigaBait · 07-15-2009, 07:51 PM

Start at the panel check obvious stuff first. Then,start breaking some of the taps at the lights apart, try to narrow my search.

drsparky · 07-15-2009, 07:52 PM

First I would check input on both legs. L1 to N L2 to N, L1 to L2, L1 and L2 to ground. What do I get?
Chuck

TOOL_5150 · 07-15-2009, 07:58 PM

I would check all the voltages as mentioned above, including N - G, just because. THen id figure out the best place to isolate parts of the ciruit, and break it into parts. I would take a look at the outside HID and see if its in good shape, and probably check that specifically as well.

~Matt

NolaTigaBait · 07-15-2009, 08:00 PM

Am i missing something?....Why check the voltage?...isn't it a dead short?

MDShunk · 07-15-2009, 08:04 PM

I bet the farmer swore as soon as you got there that "the breaker must be bad" .

480sparky · 07-15-2009, 08:07 PM

Quote:

Originally Posted by NolaTigaBait

?...isn't it a dead short?

Not necessarily. I just said it won't reset. But here's another hint: When it's turned on, it buzzes sporadically for 3-4 seconds, then opens.

Quote:

Originally Posted by MDShunk

I bet the farmer swore as soon as you got there that "the breaker must be bad" .

Actually, he wasn't even home. He always leaves the barn open, so I just went out first thing this morning before it got hot.

crazyboy · 07-15-2009, 08:07 PM

Quote:

Originally Posted by NolaTigaBait

Am i missing something?....Why check the voltage?...isn't it a dead short?

Could be a faulty breaker. I'd check all the voltages in the panel, and see if the breaker has voltage without the circuit. Then reconnect the circuit split it in the middle somewhere and try to narrow down my search to a smaller area of the circuit.

TOOL_5150 · 07-15-2009, 08:08 PM

Quote:

Originally Posted by NolaTigaBait

Am i missing something?....Why check the voltage?...isn't it a dead short?

I check everything - no matter what the customer tells me. That is a key part of troubleshooting the correct way.

~Matt

knowshorts · 07-15-2009, 08:09 PM

Check load from bad breaker from known good breaker?

steelersman · 07-15-2009, 08:38 PM

swap out breaker that won't reset with one of the known good ones to see if it resets.

TOOL_5150 · 07-15-2009, 08:39 PM

Quote:

Originally Posted by steelersman

swap out breaker that won't reset with one of the known good ones to see if it resets.

You wouldnt just pull the wire from the breaker and see if holds first?

~matt

steelersman · 07-15-2009, 08:41 PM

Nope. That would make too much sense and be to easy! I like to do more work than necessary!

TOOL_5150 · 07-15-2009, 08:46 PM

Quote:

Originally Posted by steelersman

Nope. That would make too much sense and be to easy! I like to do more work than necessary!

Ahh, you must get paid hourly as well

~matt

Black4Truck · 07-15-2009, 08:53 PM

I would seperate the load at first junction box, see if breaker holds, and see if one of the fixtures has a short.

480sparky · 07-15-2009, 08:58 PM

Quote:

Originally Posted by NolaTigaBait

Start at the panel check obvious stuff first. Then,start breaking some of the taps at the lights apart, try to narrow my search.

Quote:

Originally Posted by Black4Truck

I would seperate the load at first junction box, see if breaker holds, and see if one of the fixtures has a short.

OK, so how do you determine which cable it is?

steelersman · 07-15-2009, 09:00 PM

Quote:

Originally Posted by TOOL_5150

Ahh, you must get paid hourly as well

~matt

Yes for my fulltime job, but not for my side jobs. I prefer to charge per the job at hand. I can make much more that way.

InPhase277 · 07-15-2009, 09:03 PM

First thing I do is stick a meter in there and see what voltages I got, just as a first principle. The next thing I do is pull the wire off the breaker and see if it holds. If it does, I put the wire back on and see if I can get an amp reading.

If it stays on for more than a second or two, it is unlikely to be a dead short. At 3 or 4 seconds, knowing it is a lighting circuit, I'd suspect a bad ballast.

Then, I'd call the plumber and tell him I found out why the drains were clogged.

Black4Truck · 07-15-2009, 09:04 PM

Quote:

Originally Posted by 480sparky

OK, so how do you determine which cable it is?

Disconnect hot, neutral, and ground and push wire up into pipe

InPhase277 · 07-15-2009, 09:07 PM

Quote:

Originally Posted by Black4Truck

Disconnect hot, neutral, and ground and push wire up into pipe

Nah, too much work. Take your hot stick and find out which one isn't hot