Using Metal Box for Ground


Old 09-03-16, 12:15 PM
Thread Starter
Join Date: Sep 2016
Posts: 1
Received 0 Votes on 0 Posts
Using Metal Box for Ground

I would like to replace some two prong outlets with 3 prong outlets. The outlet boxes are metal and I was planing on using them as a path for the ground wire. When I tested the outlet the readings are hot to neutral 119v, neutral to box .4v and hot to box 24v. I realize I cannot use the box for ground but can anyone tell me what this might mean?
Sponsored Links
Old 09-03-16, 12:30 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 59,253
Received 1,122 Votes on 1,042 Posts
Welcome to the forums.

It means the box is not grounded.

If it's an older house it may use two wire NM cable with no ground or possibly metallic clad cable and the clamps in the box aren't tight.
Old 09-03-16, 12:58 PM
Handyone's Avatar
Join Date: Aug 2000
Location: U.S.
Posts: 5,450
Received 0 Votes on 0 Posts
You can replace the receptacles with GFCI's, but there will be no true equipment ground. It's better than nothing.

I live in an older home. I simply replaced the receptacles with new 2-prongs. Many household items don't use a 3-prong cord.

Anywhere I wanted a 3-prong receptacle, I ran new circuits.
Old 09-03-16, 02:25 PM
ray2047's Avatar
Join Date: Mar 2006
Location: USA
Posts: 33,583
Received 13 Votes on 11 Posts
When I tested the outlet the readings are hot to neutral 119v, neutral to box .4v and hot to box 24v
You were probably using a digital multimeter. With an analog multimeter you might have shown a more true reading of ~0 volts hot to the metal box.
Old 09-03-16, 04:23 PM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 15,151
Received 87 Votes on 74 Posts
You may find it hard to fit a gfi in the older small boxes. A gfi breaker can be used.
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: