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Author Topic: GFCI Troubleshooting  (Read 824 times)

Mike Sokol

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GFCI Troubleshooting
« on: July 31, 2017, 08:30:18 am »

I just spent two hours at my Mother-in-Law's house diagnosing a power outage in the basement. My son hooked up an outside water fountain, which ran for 30 seconds then shut down. He diagnosed it to lost power on an outside porch receptacle which I suspected was due to a GFCI tripping. However, that wasn't a GFCI receptacle, nor was there any GFCI circuit breakers in the service panel. The refrigerator in the basement was also off, and a little sleuthing showed that all of the wall receptacles in the basement were dead. More snooping found an outside street light was dead, even though it was controlled from a 3-gang switch with the other two circuits in that box operating. I pulled the cover off the service panel out in the garage and metered the clearly marked "basement" circuit breaker, but it was operating perfectly. I also confirmed there wasn't an open neutral feeding that branch circuit by metering the dead receptacles from hot to ground. Still no joy. All the while I was looking for any receptacle GFCI that could be feeding this branch circuit. There were a few in the bathrooms and kitchen, but nothing feeding the basement, outside light, and outside porch. Ugh.

I kept asking if she had seen any GFCI receptacles that looked like the one in the kitchen, but she said no.

The house was built in 2000  and the service panel neatly wired. So I opened up a receptacle in the basement for a visual inspection and noticed the sloppy wiring there. My guess was that a journeyman electrician had wired the service panel in the garage (this is in a large development with a dozen houses being built at the same time), but that an "assistant" wired all the receptacles. There was too much copper exposed , and incomplete wraps around the receptacle screws. Just generally sloppy workmanship, so I suspected the possibility of a lost connection in the branch circuit even though that didn't fit the tripping GFCI/Fountain scenario. But you need to not get too focused on a single theory when troubleshooting. So I started opening up dead outlets looking for where the branch circuit entered. Essentially, I was looking for an outlet with power that wasn't passing it down the line. As I was at it I cleaned up any obvious sloppy wiring in the receptacle boxes. Still no joy so I worked my way upstairs to the garage where I found another dead outlet on the wall opposite of the service panel. So I asked my MIL where any other outlets in the garage were. She pointed out the a few more obvious ones on the other walls, and they were also dead. Then she asked if I had seen the one by the window that was 5 feet away from the service panel. Well I couldn't see it at first because there were paint cans and boxes piled in front of it on the workbench. After digging it out I found a GFCI receptacle that was tripped. And plugged into it was a power supply for her VOIP phone service. She had neglected to tell me that her house phone also went dead at the same time as the fountain, so she went out and bought a new telephone since she thought it had just died.

So the circuit breaker marked "basement" first fed this one GFCI outlet on the workbench next to it, snaked around to two more garage outlets, went to one of the switches in the 3-gang wall plate in the hallway, then powered the two receptacles on the back porch with the fountain, then finally dived into the basement where it looped around to four wall mounted outlets. The fix was just to reset the one GFCI receptacle and it all powered up. Ugh...
« Last Edit: July 31, 2017, 11:15:29 am by Mike Sokol »
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John Roberts {JR}

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Re: GFCI Troubleshooting
« Reply #1 on: July 31, 2017, 09:35:04 am »

Is it plugged in maam?

JR
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TJ (Tom) Cornish

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Re: GFCI Troubleshooting
« Reply #2 on: July 31, 2017, 09:39:11 am »

I just spent two hours at my Mother-in-Law's house diagnosing a power outage in the basement. My son hooked up an outside water fountain, which ran for 30 seconds then shut down. He diagnosed it to lost power on an outside porch receptacle which I suspected was due to a GFCI tripping. However, that wasn't a GFCI receptacle, nor was there any GFCI circuit breakers in the service panel. The refrigerator in the basement was also off, and a little sleuthing showed that all of the wall receptacles in the basement were dead. More snooping found an outside street light was dead, even though it was controlled from a 3-gang switch with the other two circuits in that box operating. I pulled the cover off the service panel out in the garage and metered the clearly marked "basement" circuit breaker, but it was operating perfectly. I also confirmed there wasn't an open neutral feeding that branch circuit by metering the dead receptacles from hot to ground. Still no joy. All the while I was looking for any receptacle GFCI that could be feeding this branch circuit. There were a few in the bathrooms and kitchen, but nothing feeding the basement, outside light, and outside porch. Ugh.

I kept asking if she had seen any GFCI receptacles that looked like the one in the kitchen, but she said no.

The house was built in 2000  and the service panel neatly wired. So I opened up a receptacle in the basement for a visual inspection and noticed the sloppy wiring there. My guess was that a journeyman electrician had wired the service panel in the garage (this is in a large development with a dozen houses being built at the same time), but that an "assistant" wired all the receptacles. There was too copper exposed , and incomplete wraps around the receptacle screws. Just generally sloppy workmanship, so I suspected the possibility of a lost connection in the branch circuit even though that didn't fit the tripping GFCI/Fountain scenario. But you need to not get too focused on a single theory when troubleshooting. So I started opening up dead outlets looking for where the branch circuit entered. Essentially, I was looking for an outlet with power that wasn't passing it down the line. As I was at it I was cleaning up any obvious sloppy wiring in the receptacle boxes. Still no joy and I worked my way upstairs to the garage where I found another dead outlet on the wall opposite of the service panel. So I asked my MIL where any other outlets in the garage were. She pointed out the a few more obvious ones on the other walls, and they were also dead. Then she asked if I had seen the one by the window that was 5 feet away from the service panel. Well I couldn't see it at first because there were paint cans and boxes piled in front of it on the workbench. After digging it out I found a GFCI receptacle that was tripped. And plugged into it was a power supply for her VOIP phone service. She had neglected to tell me that her house phone went dead at the same time as the fountain, but she went out and bought a new telephone since she thought it had just died.

So the circuit breaker marked "basement" first fed this one GFCI outlet on the workbench next to it, snaked around to two more garage outlets, went to one of the switches the 3-gang wall plate in the hallway, then powered the two receptacles on the back porch with the fountain, then finally dived into the basement where it looped around to four wall mounted outlets. The fix was just to reset the one GFCI receptacle and it all powered up. Ugh...
Fun stuff.  My house was built in 1995 so conventional breakers, but GFCI receptacles where needed by code at the time.  I was changing out the recessed lighting in my basement, which required replacing the conventional breakers with in my case a $200 special order 2-pole arc fault breaker, as the circuit I was working on was part of a multi-wire branch circuit. The new breaker would trip when any load was placed on either circuit.  Multiple hours of troubleshooting later, aided by a high-resolution resistance measurement that gave me some indication of where the erroneous G/N bond was, I found a bare bulb socket in our storage room where the electrician landed both the ground and neutral wire on the same terminal.  It was the end of the line, and I guess he didn't know what else to do with a ground wire with no place to put it.

I wish the price difference between GFCI breakers and GFCI receptacles wasn't so great.  If the GFCI breaker was $20 instead of $50+, there would be less motivation to string half the house off a $10 GFCI receptacle 3 rooms away.

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Keith Broughton

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Re: GFCI Troubleshooting
« Reply #3 on: July 31, 2017, 10:01:09 am »

So let me get this straight...
If you link other receptacles from a GFCI  receptacle, the GFCI controls the power down stream?
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TJ (Tom) Cornish

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Re: GFCI Troubleshooting
« Reply #4 on: July 31, 2017, 10:13:23 am »

So let me get this straight...
If you link other receptacles from a GFCI  receptacle, the GFCI controls the power down stream?
It depends how you wire them.  GFCI devices have "Line" and "Load" terminals.  The GFCI receptacle is fed from the Line terminals.  If you tie your downstream receptacles to the "Load" terminals, then yes the GFCI device will protect everything downstream of that, which may or may not be what you want.  If you only want the GFCI device to protect that particular receptacle, you need to feed downstream things from the "Line" side of the GFCI - either with a second set of "line" screw terminals if the device has them (most don't), or by wirenutting your downstream things to power upstream of the GFCI.
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Mike Sokol

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Re: GFCI Troubleshooting
« Reply #5 on: July 31, 2017, 11:11:22 am »

It depends how you wire them.  GFCI devices have "Line" and "Load" terminals.  The GFCI receptacle is fed from the Line terminals.  If you tie your downstream receptacles to the "Load" terminals, then yes the GFCI device will protect everything downstream of that, which may or may not be what you want. 

Yeah. And if that particular GFCI outlet is hidden behind a door or cabinet, you can have one heck of a time discovering where it's located when it trips. Don't expect your customer (or Mother in Law) to have a clue as to the location of any GFCI outlets. So the best thing I can do is start discovering where all the dead outlets are located, then try to imagine where the branch circuit wiring must have been run inside the walls. I hate residential wiring...   

Mike Sokol

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Re: GFCI Troubleshooting
« Reply #6 on: July 31, 2017, 11:33:03 am »

She did promise to make me a dozen Yellow Pickled Eggs for my troubles, so it was worth it....

http://allrecipes.com/recipe/70505/yellow-pickled-eggs/

John Roberts {JR}

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Re: GFCI Troubleshooting
« Reply #7 on: July 31, 2017, 12:00:13 pm »

Yeah. And if that particular GFCI outlet is hidden behind a door or cabinet, you can have one heck of a time discovering where it's located when it trips. Don't expect your customer (or Mother in Law) to have a clue as to the location of any GFCI outlets. So the best thing I can do is start discovering where all the dead outlets are located, then try to imagine where the branch circuit wiring must have been run inside the walls. I hate residential wiring...
Yup.. in some version of the future GFCI (or whatever replaces them) can report their status wirelessly. I can also imagine how useless that is if you don't know where outlet #Ab235 is located. ::)  Maybe a beeper in addition to the red LED could help?

Did you use your NCVT to trace out the wiring behind the walls? My cheap NCVT is so sensitive it can read wires inside the walls so could ID where the power stopped, or if it was getting into an outlet, but not out of it.

Did you also have to fix the fountain that tripped the GFCI, or was that unrelated, or a ghost trip.  Ghost trips for hidden GFCI outlets are even more of a PIA...  My dishwasher is plugged into a GFCI outlet on the other side of the wall from my kitchen. I didn't realize the GFCI had tripped until I went into the laundry room to check on the power because the dishwasher was unresponsive, and saw the bright red LED. 

JR
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Stephen Swaffer

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Re: GFCI Troubleshooting
« Reply #8 on: July 31, 2017, 12:38:36 pm »

The other real pain is when someone installs GFCI receptacle in (typically) a kitchen retrofit and doesn't understand what the load termianls are for-so all the GFCI's are wired in series.  A test may trip any or allof them and if you don't realize it it appears the first one you tested just died permanently.

Since almost all places in a resi home now require AFCI breakers and the difference in cost between an AFCI and an AFCI/GFCI combo breaker is < than the cost of a GFCI receptacle, I think you will see fewer GFCI receptacles in new resi construction-I know I quit using the.  That really helps with the hidden receptacles.
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Mike Sokol

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Re: GFCI Troubleshooting
« Reply #9 on: July 31, 2017, 01:05:54 pm »

Did you use your NCVT to trace out the wiring behind the walls? My cheap NCVT is so sensitive it can read wires inside the walls so could ID where the power stopped, or if it was getting into an outlet, but not out of it.

No, but that was my next step if I didn't find it visually. The plan was to shut off all the other circuit breakers and just leave on the "basement" breaker. I have a variable sensitivity NCVT so it could have been used as a Fox & Hound tracer. Or at least that was the plan.
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Did you also have to fix the fountain that tripped the GFCI, or was that unrelated, or a ghost trip.  Ghost trips for hidden GFCI outlets are even more of a PIA... 

No, but the kids had dug all of the muck out of the little pump. When they turned it on it tripped in about 30 seconds. After I got the GFCI back on the fountain worked perfectly. So a ghost trip of some sort. Glad she didn't call an electrician first as I don't think he would have found it any quicker than I did, and that would a pretty hefty bill just to reset a GFCI.
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