I have a new oven/micro unit just delivered. It has a 4 wire pigtail and the old unit had a 3 prong 30a plug to a 3 prong female wall plug. Can I use the same wall outlet and plug or do I need to change out the wall outlet to a four prong receptacle? Anyone?

  • Hello, and welcome to Home Improvement. This question has already been answered here; please check it out. Commented Dec 21, 2018 at 21:47
  • 1
    Possible duplicate of How do I connect a dryer with a four prong plug to a three prong socket? Commented Dec 21, 2018 at 21:48
  • While the linked dup is a similar question, I’m not sure that changing the cord to 3-prong is the best answer for this question.
    – Tyson
    Commented Dec 21, 2018 at 22:41
  • Can you turn the breaker for the oven off then post a photo of the inside of the outlet box for the oven receptacle? Commented Dec 21, 2018 at 22:58

1 Answer 1


It's possible the newest units are simply not made for a 3-prong receptacle (and that would be reasonable since grounds are important to protect electronics from people).

In that case, and regardless for safety, you have the ability to retrofit ground. This involves running a #10 bare wire via any achievable route back to any of several locations:

  • the service panel the power comes out of
  • any other appliance or junction which has a #10 ground wire or larger going back to that same panel
  • the grounding electrode wire that grounds the service panel to your water pipe or ground rods

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.