Electrical – Open ground on all outlets, voltage meter beeping on metal boxes and MC cable

electricalgroundingwiring

I'm installing a new switch and outlet in a previously renovated garage, and I noticed the following:

  1. My Klein non-contact voltage tester beeps continuously on all of the metal boxes and surface-mounted MC cable.
  2. The voltage tester beeps continuously when I touch it to parts of the wood framing (rafters) and even the door hinges.
  3. All of the outlets are showing open ground using a three-light plug-in tester
  4. When I use a pin-type voltage tester to check the wiring, HOT to GROUND shows nothing, HOT to BOX/MC CABLE shows nothing. HOT to NEUTRAL shows 120V. Finally, BOX/MC CABLE to NEUTRAL shows nothing.

I've checked all of the boxes, outlets and switches in the garage, and the wiring is fine.

Any ideas for next steps?

Best Answer

Well, don't trust the no-contact tester to tell you anything but the presence of voltage somewhere close to the end of it. Beyond that they aren't much use.

From what you said in #4 you have an open ground. Also, if you used a 3 light tester and it told you you have an open ground, I would believe that.

Check your equipment ground connections for a bad splice and terminations for a loose connection. Also, if this is a garage with a sub-panel it is possible they miswired it and your ground back to the main is open somewhere.

Good luck and stay safe by working with the circuits off!

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