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smh12

Upgrade 3 prong to 4-prong dryer receptacle question

smh12
16 years ago

We have purchased a new dryer that has a 4 prong cord. Our current receptacle is the older 3 prong. I have been told to purchase a nema 10-40 to replace my 10-30. I have black, red and white wires and what looks to be a bare copper wire (ground?)not connected to the receptacle but to the back of the box. Is this considered the 4th wire and shouldn't it be green? Can I install this new receptacle or do I need a new run from the panel? Thanks

Comments (8)

  • normel
    16 years ago

    The ground may be green or bare. If you have all four wires at the receptacle, you can connect the new 4prong receptacle without having to run new wire.

  • radioguy4ever
    16 years ago

    smh12, the wiring you have is correct, but you will most likely have to change the receptacle itself to one that accepts a 4 prong cord. the wiring instructions with the new receptacle will show you what wires go where.

  • smh12
    Original Author
    16 years ago

    Is it normal for a home built in 1995 to have a bare copper wire in the back of the box instead of a green wire?

  • radioguy4ever
    16 years ago

    smh, yes it is. the bare copper comes from inside the "romex" wiring of the home. most likely, when the dryer was installed it was a 3 prong, but the builder knew enough to make sure it could be "upgraded" later on ny running the 3 wire + ground setup.

  • smh12
    Original Author
    16 years ago

    ok, new 4 prong receptacle is installed. Now I guess I need a new box/faceplate in/on the wall...the new 4 prong won't quite fit. Is there any certain kind I need? Is it better to use metal vs plastic? Can you tell I've never done this before...

  • bigbird_1
    16 years ago

    "ok, new 4 prong receptacle is installed. "
    Did you wire the new receptacle without seeing if it will attach to the old box?

    Use a square 4 11/16" box, designed specifically for dryer/stove receptacles. We mostly use metal boxes in Canada. Plastic boxes are much more expensive here.
    The receptacle is the "faceplate" as you call it.

  • cobraguy
    16 years ago

    smh..are you saying the new 4 prong receptacle is installed in the box and the existing faceplate won't fit?

  • smh12
    Original Author
    16 years ago

    cobraguy- I guess "installed" was the wrong word. The new receptacle is wired and hanging out of the current, too small, box (power off at main). I didn't even think about seeing if I needed a new box...it looked like it would fit the same as the old. I guess I was wrong. I now have a new square metal box to install and still need to get a faceplate for the outside.