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Thank you for your much appreciated responses.

I am getting a new washer and dryer. Since the new dryer will use the 4-wire cable and my old one used a 3-wire cable I need to update the in-wall receptacle to add a GND wire. The old in-wall receptacle non metal box did not have a GND wire so I brought the GND from an existing GND in another close by in wall-receptacle GND connection. The new GND wire is screwed to a new metal receptacle box and to the new receptacle plug at the GND connection. The new outlet has GND, X, Y, and NEUTRAL. The two hot wires are attached one to X and one to Y. When the metal receptacle bracket is not screwed to the metal receptacle box there is no short. But when I screw the new 4-wire receptacle bracket to the metal box and turn the breaker back on it snaps the breaker. Sorry, I'm having difficulty getting a picture loaded. The old dryer is a 20 year old Frigidaire and the new one is a Whirlpool that is not yet connected so there will not be a neutral/GND bond. This is all happening without plugging the new dryer in, just connecting the new in-wall receptacle.

When the receptacle bracket is not screwed in as in the pic and the breaker is powered it appears normal and does not break. When the bracket gets screwed to the box as would be normal and the breaker is powered it breaks.

How can I figure out what's wired wrong here?

Black, Red, White, Green wires on back of 240V receptacle

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    Pictures please! Also, what model of dryer and did you make sure to remove the neutral/ground bond from the dryer? Sep 8, 2023 at 2:03
  • we are missing lots of information to be able to answer this, a photo would be good
    – Traveler
    Sep 8, 2023 at 3:36
  • Can you clarify what exactly you are doing when "Changing from a 3 wire dryer outlet to 4 wire according to online info"? Are you replacing an in-wall receptacle? Plugging in an adapter? Changing the plug on your dryer cord?
    – Armand
    Sep 8, 2023 at 5:10
  • upload the picture to imgur.com, paste the "share" link in your question. Someone will embed the image for you.
    – FreeMan
    Sep 8, 2023 at 11:27
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    How do you know there is no short when the receptacle bracket is not screwed in - did you try turning on the breaker with the bracket not screwed in as pictured?
    – Armand
    Sep 8, 2023 at 17:51

1 Answer 1

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Symptom likely cause: It looks like your in-wall metal box does not have ground connected to it, but you have ground connected to the receptacle. Thus, when you screw the receptacle to the box, the ground from the receptacle (which should be connected internally to its metal face) is connected electrically to the metal box. Somehow the metal box is energized/hot, so with ground now connected to it, you have a short and the breaker trips.

Likely root cause: Most likely one of the black or red wires has damaged insulation and is touching the metal box, or when pushing the receptacle into the box, one of the black or metal wire stripped or otherwise damaged/bare sections is pushed against the metal box or the screws used to secure the receptacle.

What to do:

First, ground must be connected to BOTH the metal box and the ground screw on the receptacle. Get two 10 gauge green/bare grounding wire pigtails; attach one to a standard green ground screw that screws into the appropriately-sized hole in the back or side of the metal box; attach the other pigtail to the outlet ground screw in place of your existing ground wire. Finally, use an appropriate wire nut or Wago to connect the loose ends of the two pigtails to the original ground wire end.

Now, if the short is between a red/black wire and the box, the breaker should trip even if the receptacle is not screwed in. If instead the short comes from pushing/bending the wires and the receptacle into the box, the breaker should only trip once you do that.

Either way, you can more closely inspect the black and red wires to figure out where the short is happening. Pay special attention to the opening/clamp where the wires come into the side of the box - make sure there is a proper clamp/connector there with no sharp edge or damage to the wire insulation.

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