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I had my garage slab removed and during the jackhammering phase, a GFCI circuit breaker tripped and would not reset (It would immediately trip when I turned it back on). I replaced the breaker with a brand new GFCI circuit breaker but the issue was not resolved. I can confirm the circuit breaker is installed correctly. I opened and inspected all of the outlets, switches, and light sockets associated with this circuit and did not see anything amiss.

An electrician has been contracted but they will not be on site for several days. I am interested in attempting a resolution on my own prior to their arrival.

What are some troubleshooting steps I can perform to try to resolve the fault?

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  • I would pull the breaker and measure the continuity from the hot to neutral making sure nothing is plugged in. The vibrations may have cut the insulation causing the leakage.
    – Ed Beal
    May 21 at 17:57
  • Was the wiring under the garage slab in conduit? So you have not yet poured the new slab? May 21 at 23:55

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Instead of jumping to the conclusion that an expensive safety device is faulty and replacing it, look at the wiring itself. Somewhere, likely near where the concrete was broken up, there are loose or damaged wires. The fact that the old breaker and the new one are tripping is a very strong indicator that they're doing their job of saving your life and preventing your house from burning down.

You indicate that you opened & inspected all boxes on the circuit. Either you missed one, or a wire was cut between boxes, or your inspection wasn't thorough.

I'd suggest a re-inspection:

  • Power off (easy one)
  • Open a box (preferably closest to the breaker)
  • Pull the devices out of the box but do NOT disconnect anything.
  • Label cables to identify where they go.
  • Take a picture of all the wiring with the labels showing
  • Remove all the cables, put wire nuts on them all
  • See if the breaker will turn on
    • if the breaker turns on, the problem was in the wiring in the box or further down the line.
    • If the breaker doesn't turn on, it's between the breaker & this box.
  • Wire up just one device in this box (ignoring everything down stream).
  • Test the breaker for functionality again.

Lather. Rinse. Repeat. those last 3 steps - disconnect everything, test the breaker, add one item at a time. So long as the breaker/GFCI will turn on and stay on after each step, you're doing it right. Make sure you turn the power back off before going back to the box to do more work!

If/when you get to a device that will trip the breaker every time it's turned on, then you've got a bad device (it's possible, they do fail over time). Replace that one device, then continue your process.

Be sure to label every wire & device and take pictures before you disassemble to ensure you get it put back together the same way. Assuming no wiring changes were made, you'll have a correctly wired system when you're done, too.

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    This is great advice! I will get started on this immediately.
    – Alex Block
    May 21 at 18:30
  • @Alex I think giving it the old Mark 1 eyeball is better than nothing, but really, you should be disconnecting sections of the circuit to figure out where the fault is. Remember you must disconnect both hot and neutral, but leave ground where it is. May 21 at 23:38
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Disconnect parts of the circuit. If power gets from the GFCI breaker to the first device with all other devices disconnected, the fault is not in that piece of (cable, or conduit and wires,)

Then connect the next device (only) until you find one where the GFCI trips. The (cable, or conduit and wires) between that device and the last device where it worked is the one with the (or a, if there are multiple faults) fault.

If you can't get the first device to work, there is a fault between the breaker and the first device. If you know where the jackhammering was going on when it tripped and where the wiring runs, you might be able to make a guess as to where the fault is and get there faster than the "check each device" method.

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