Return to the Electrical Wiring Forum | Post a Follow-Up

2 to 3 prong outlets older home

Posted by johnc777 (My Page) on
Sat, Feb 15, 14 at 10:48

Kind of a generic technical question. The usual answer is to use a GFCI and the little tag. Are there any situations where a regular 3 prong outlet can be used?

I'm thinking about house with metal conduit. How about flexible metal? AC would be ok but old true BX no? How about Romex with the small ground wire?


Follow-Up Postings:

RE: 2 to 3 prong outlets older home

A properly installed metal conduit can be the ground. If you install it right, you can install a grounded receptacle using the ground from the conduit.

The armor of old BX is not a sufficient ground. Neither is current type MC (though it will typically have a grounding conductor other than the armor). Type AC's armor (and it's integral bonding strip) can be used as a ground.

Type NM (ROMEX) with a ground wire is OK. Most of the smaller stuff (12, 14) has a full size ground (it's just bare). Larger stuff has a smaller grounding conductor because such is an acceptable size.

Art. 250.130(C) allows the extension of a ungrounded branch circuit to be connected to certain grounds to pick up the equipment ground.

 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!

Return to the Electrical Wiring Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.

Learn more about in-text links on this page here