Shorted Box with Multimeter

mikezusaSeptember 20, 2013

Just as I was getting more confident in my electrical ability I took two steps backwards this morning.

I wanted to test an outlet ( I didnt remove it and was doing it while mounted in the box) I placed my red probe on the hot screw and a few moments laters sparks flew and breaker tripped.

I came in contact with the side of the box. I assume thats a ground fault (or was this a dead short?). I arc welded a small nick in the box and some black appeared on the box and the wall next to it. My red test probe also has a small melted spot on the metal.

I then reset the GE breaker (it was in the halfway position between off and on I think, wasnt in the fully 'off' position).

WIth the power off I replaced the outlet that was charred a bit at the brass screw. Of the wiring I saw in the box I did not see any melted insultation. Turned back on and everything seems OK but I am concerned about what happened.

Do you think I damaged the circuit breaker or the wiring because of this?? WIth sparks flying and charring do you think I have fire hazard now in the wall??

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randy427

It was a dead short to ground and the CB worked as intended.
I doubt there was any damage to the CB or wiring, or even to the receptacle.

    Bookmark   September 20, 2013 at 11:39AM
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Ron Natalie

The "halfway" position is how GE (and many other breakers) trip. You need to move it full off and then back on to reset it.

As Randy said, things appeared to have functioned normally. Now you also see why we require connections to be made inside boxes.

    Bookmark   September 20, 2013 at 1:55PM
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mikezusa

Thanks. I think next time (after I replace my melted probe) I will need to remove an outlet from the box before testing.

My hands are kind of shakey and getting at the screws from the side still mounted was kind of like playing "Operation" with a 120 volts.

    Bookmark   September 20, 2013 at 3:34PM
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mike_kaiser_gw

If you're just testing to see if there's power, you can just stick the probe into the hot slot of the receptacle.

If you want to do it from the side, try some decaf! ;-) There are probes that are insulated so that just the tip is exposed or you could wrap a bit of electrical tape around the probe to increase your margin of error.

    Bookmark   September 21, 2013 at 9:24AM
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mikezusa

"If you're just testing to see if there's power, you can just stick the probe into the hot slot of the receptacle. "

Thats when my hand gets shakey!! My anxiety level goes up when I go to insert the probe. I did that once with the negative probe plugged into the amp setting and I got sparks.

Better yet, I think I need a non-contact voltmeter.... Im looking at the FLUKE T6.

    Bookmark   September 21, 2013 at 3:15PM
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