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While running wire for a new dedicated outlet, I found 10/3 supplying my 3-prong dryer outlet. Removed the receptacle and discovered that the ground wire is just sitting unconnected in the outlet box. I checked and found 120v between either hot and the neutral. Is there an existing configuration with which this is completely safe? Or should a 4 prong outlet and plug be installed before resuming use?

Photos of dryer connections:

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    Nema 10 circuits were ban in 96 from being installed for being unsafe(deadly). You got ground and if ground is connected at the panel, going for four prong is a no brainer
    – crip659
    Commented Jun 19 at 19:44
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    Since the ground wire existed in the box, it was illegal to install the NEMA 10-30. The 10-30 exception which was valid from 1965-1993 only applied when no ground is present.
    – Harper - Reinstate Monica
    Commented Jun 20 at 21:33
  • @Harper-ReinstateMonica Today I discovered that the ground wire is screwed into the bottom of the breaker box at the other end. It’s the main panel and it’s metal. If I wire a 14-30 receptacle, does that mean the ground wire will send current into the breaker box?
    – Justin
    Commented Jun 20 at 21:45
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    No, that's OK. As long as the other end (i.e., your 14-30 receptacle and the dryer cord and the dryer) is all wired correctly, ground will only carry current if there is an actual fault, which is what it is designed for. That being said, the ground wire should be screwed into the ground bar or neutral bar, not just into the metal case of the panel box. But practically speaking (not to code!) any ground connected to the metal case will function properly - that's in fact how grounding via metal conduit works.
    – manassehkatz-Moving 2 Codidact
    Commented Jun 20 at 23:26
  • Awesome. Thank you so much for this feedback. VERY much appreciated. Now I can finish wiring my dryer and new receptacle. Thanks again.
    – Justin
    Commented Jun 20 at 23:41

1 Answer 1

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Install a new 14-30 receptacle.

It is very likely that:

  • House was built with a 14-30
  • Homeowner either bought a used dryer that already had a 3-prong plug/cord attached or moved their dryer with a 3-prong plug from their previous home.
  • Instead of replacing the cord/plug on the dryer with a 4-prong plug/cord which is really, really easy to do, they replaced the receptacle with an obsolete 10-30 receptacle.

The absolutely correct and safe thing to do is to:

  • Replace the 10-30 receptacle with a properly grounded 14-30 receptacle
  • Replace the 3-prong plug/cord on the dryer with a 4-prong plug/cord
  • Remove the neutral/ground bond (usually one screw/wire) from the dryer

Are you required to do that? Probably not. But it is a very good idea, costs very little and significantly increases safety.

If you are not 100% certain that you have removed the neutral/ground bond from the dryer, just set your multimeter on continuity and you should find that with the dryer unplugged if you test neutral prong to ground prong it should be no continuity, neutral to bare metal case no continuity, ground to bare metal case yes continuity.

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    Great, detailed response. Thank you. I’m currently trying to remove the neutral/ground bond from the dryer. It looks like there are two ground wires attached to the frame. One wire comes off the frame and links into the middle (neutral?) connector. The other sits a few inches away and it follows all of the devices’ other wires up through a hole near the top of the box. (Picture added to original post). Is the ground wire from the frame to the middle connector the one that needs to be removed?
    – Justin
    Commented Jun 19 at 21:17
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    Picture isn't too clear (to me at least). But based on your description, yes it sounds like the "wire to the middle connector". Again, I would test with a multimeter to be sure.
    – manassehkatz-Moving 2 Codidact
    Commented Jun 19 at 21:21
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    Or, @Justin, ask a whole new question including the brand/model of the dryer. Someone will look up the manual for you (ahem) where the instructions on exactly how to remove the neutral/ground bond.
    – FreeMan
    Commented Jun 20 at 15:00
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    Does that grey wire appear to be badly connected to the crimps?
    – Andrew Morton
    Commented Jun 20 at 16:34
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    (a) the make/model (or at least "series" or similar) is often on the front panel - e.g., "Kenmore 80 Series"; (b) there should be a serial number plate somewhere - sometimes visible inside only when opening the door, sometimes on the back.
    – manassehkatz-Moving 2 Codidact
    Commented Jun 20 at 17:50

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