Troubleshooting

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boboelectric

Senior Member
I dodged my hardest one. A customer called for an exterior GFCI
receptacle that wasn't working. Sounded easy. Before I went, he called back. His wife had reminded him that the exterior receptacle was controlled by a light switch in the house (something they thought they needed when they built the house, in case they wanted to turn christmas lights on and off).

I don't know how long it would have taken, but there sure would have been a lot of other boxes & etc. took apart before I would have started checking light switches.
Had the same thing last week. Nothing like swimming around in wet mulch.
(Oh, There's a switch)
Took me 45 mins.
 
Customer called stating everytime he dove into the swimming pool he got shocked. Spent 3 hours going over every item in the wiring. Finally checked the neutral. Bad neutral at the meter, including the main bonding jumper. Circuits with a neutral were trying to feed through the pool steel bond. Tightened the neutral at the meter - solved.
 
Dam where do I start on this one...a bad lightning arrestor can be hard to find. But probably the hardest was on a JSIIDS system. JSIIDS is a security system developed by uncle sam in the 50s or 60s and probably state of the art for the time. It's obsolete now so there are no OPSEC issues. But it was used up until the late 90s. About once a week this one bldg would go off in the middle of the night. Checked everything out, asked building custodians to arm/dearm the system...no problems there. Problem was getting worse but not locking in what zone. Experiance had taught me that bad cards wouldn't always register which zone. Replaced all cards, sensors, mother board even the wiring harness. Eventually sat in front of the panel most of the night with a meter attatched to each zone card...waiting to see one activate...so of course nothing happens. Did it another night and the cops got an alarm but I had nothing. Turned out to be a bad receiving module in the cop station. So glad they finally got rid of that system.
 

dmagyar

Senior Member
Location
Rocklin, Ca.
3 ways, mixed travelers with neutrals

3 ways, mixed travelers with neutrals

I had a GC friend of mine call me for a problem he encountered. He opened a junction box and got shocked between the metal box and the neutral, which was still connected, but he had just removed the wirenut. He couldn't figure out how he had gotten shocked from the neutral without being in series with a load. I also told him jokingly that he got shocked for trying to do electrical work without being qualified.

After I got to the job sure enough there was 120 volts to ground from this neutral. As I looked a little deeper I saw that someone had tied the neutrals to the travelers in the switch boxes. All of the three ways in the house had been done the same way. It took opening up quite a few of the lighting switch boxes in the house to get everything back to how it should have been to start with. As long as the lights were in series between the connnection of the travelers to the neutral nothing shorted out. This was not a small, inexpensive house; it is in a large gated exclusive community. But low bid does get the job.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
After I got to the job sure enough there was 120 volts to ground from this neutral. As I looked a little deeper I saw that someone had tied the neutrals to the travelers in the switch boxes.
That's an important lesson: not every white wire is a grounded conductor. It's just a wire with white insulation.
 

DavidA

Member
Location
Fresno, CA
Four offices with a few thousand square feet of warehouse attached to it. The complaint: Using a 120v 12A compressor in the warehouse would shut off the computers in reception; using a saw at a different receptacle in the warehouse would shut off the computers in a different office.

Watching a meter in the reception area showed voltage spiking to 170v when the compressor started then dropped to 135v while running. Similar situation in the other office. The increase in voltage was apparently activating the plug in type power strip/surge protectors.

Main was 200A 120/208v 3 phase to one subpanel in the warehouse. Discovered 4 20A circuits piped in warehouse to 4 receptacles with 2 neutrals. Fine, no problem there...Wait, three ungrounded conductors were on A phase and the fourth was on C....

Rearranged the panel and the problem went away. I still can't figure out exactly why it was behaving this way though.
 

davet

Member
Got call half the house was out.Determined that neutral was lost.Ripped apart lite switches,plugs,lite fixtures,celing fans.All hanging free now.Nothing wrong.Went outside to have a smoke and think.Turned around and there was an outside GFCI.NAW!couldn't be that simple? Took apart and found line side neutral wire corroded and broken free.Repaired and all is well.Back inside, another 2hrs. to put all back together.( What idiot would wire the house from an outdoor GFCI ? )
 
Troubleshooting circuits in buildings is a piece of cake.

I did electrical troubleshooting in cars and trucks for years. Now THAT sorts the men from the boys.

I got called once for a Lincoln Town Car that would stall when put in gear. If you took out the tail light bulbs, the car would run fine. If you put them back in, the car would stall as soon as the brakes were applied. (Ground wire to fuel pump shared with brake light ground and came loose from body)

I got another call on a no start for a different Lincoln. I couldn't verify it as it started every time for me. The customer came to pick it up and it wouldn't start. I got in and it started fine. It would only not start when the customer tried to start it, it started fine for me every time. (Seat belt sensor failure. The customer weighed more than I did. Much more.)

I have literally dozens of stories like the above. So far (20 years on and off) I have never had an AC system I couldn't troubleshoot.

The worst of the worst, no matter what, are intermittent problems. Trust me, unless you are psychic, you have to be able to verify the complaint to stand much of a chance of success.

I LOVE troubleshooting. To me, the perfect job would be T-shooting electrical systems all day long.
 

MichaelGP3

Senior Member
I can't remember seeing this many wrong things on a single job...

I can't remember seeing this many wrong things on a single job...

On an industrial property that had been sitting idle & mostly neglected for several years, the owner decided he wanted the combination fire/security alarm brought back to working condition. What I found was a local Mirtone 790 fire alarm panel that had door switches, motion sensors (both wired normally open), smoke detectors, pull stations and fire alarm horn strobes seperately run back to said panel. All wire (I'm recalling between 20 and 30 pairs) were black 16 gauge TW, and all the wire labels had dried out, uncurled, and were laying on the bottom of the panel. No backup batteries installed. I found out that the system was armed at night by turning on the circuit breaker. An exterior light switch mounted on a bell box was wired in series with the exit door alarm contact, and was how one got out of the building without setting off the alarm. Everything was in conduit, except for the 16 volt plug-in transformers that locally powered the motion sensors. Miraculously, the Mirtone panel was ok.

I told the owner that the fire alarm would likely be salvageable, but it would be on a T&M basis, and would involve removing any security alarm wiring from the fire alarm. I identified & re-labeled the circuits, cleaned the smoke detectors, performed current draw calculations based on Mirtone 790 literature already in my possession (no drawings to work from!) & installed the correct size batteries. I also put a screw-on keeper on the circuit breaker. Tested the system, & everything worked, except for 4 horn/strobes in a high bay area. This high bay had one of those electric cranes that motors across pairs of horizontal girders painted yellow. No ground faults present. I could 'see' the EOL resistor installed at the last device with my meter at the panel, and I could read the supervision voltage from the panel at the terminals of the last device. Other devices worked on the same circuit, so I knew the output zone card in the panel was ok. I was thinking that perhaps voltage drop was the issue, which would have been consistent with what I was looking at. Maybe a bad device was clamping the reversed alarm current? But noooooo. What I found was an open junction box, not visible from the floor since it was obscured by one of the crane's horizontal girders. A Tandy analog volt/ohm meter from the 1970's with a severely corroded battery inside rested on top of this girder. Set to the ohms scale, it had its leads alligator clipped across the intact horn strobe circuit before the first device in that room. Removed the meter, closed the j-box, and I had a clean system. I can tell you that if there was a meter throwing event in the Olympics, that year I would have won.

To this day I don't have any idea if my predecessor fell, quit suddenly, forgot, or deliberately sabotaged the job.
 
What I found was an open junction box, not visible from the floor since it was obscured by one of the crane's horizontal girders. A Tandy analog volt/ohm meter from the 1970's with a severely corroded battery inside rested on top of this girder. Set to the ohms scale, it had its leads alligator clipped across the intact horn strobe circuit before the first device in that room. Removed the meter, closed the j-box, and I had a clean system.
Now THAT'S a classic!
 

lostinspace

Member
Location
Florida
parking lot lites. had 120v pole to ground and lites not working. found a junction box buried 2 feet deep with burnt up splices. had to trace the feed 200' from condo building to edge of parking lot. dug up pipe, cut it, ground wire pulled right out, used the wire to find radius of where box could be, dug for 2 hours before finding it. long, frustrating friday, but the beer tasted a little better that night:D
 

220/221

Senior Member
Location
AZ
I told him we will have to run a wire to the drain under the house to connect it to the main grounding system. He never called back. Really expensive. Must not have hurt that bad. What do you guys think? About that issue.
Your solution was only a band aid. I wouldn't have left till I found it.


I have had two shower shock calls. One was a combination of errors. I forgot the details but I do recall a broken ground wire on the 14/2 home run in a living room ceiling box coupled with another fault that energized the copper.

Another one was actually at MY house. Wife and sister in law claimed to be getting shocked in the shower. I never felt a thing. I showered in the morning, they showered at night. Every time I tested it, I found nothing. I shower at night one time and....they were right. I grabbed my wiggy and got 120V from handset to shower door frame and drain cover (cast iron).

Outside lighting on photo cell, old scuffed UF cable (NOT my work) lost a neutral but the wire was melted/contacting the ground. 50's era house with no grounds and no water bond but they tied the UF ground to the water pipe. I suppose they were thinking it would be a good safe ground but the water service had long ago been changed to plastic so again, it was a combination of errors.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
... I do recall a broken ground wire on the 14/2 home run in a living room ceiling box coupled with another fault that energized the copper.
I had a very similar one a few years ago; an intermittent problem with shocking from switches, especially in the bathroom.

In a 2g switch box in the hall, I found a splice of reduced-size EGC's, twisted only, with the wire ends pointing upward. Where the incoming feed's sheath ended, the EGC was broken.

Apparently, slowly over time, the broken wire had literally cork-screwed itself down the spiral of the twists, and eventually landed with the broken tip on one traveler terminal on a 3-way switch.

Thus, every EGC downstream of this box, bath and bedroom lights and receptacles, was energized. Stuff happens.
 
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