Using Metal Box for Ground


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Old 09-03-16, 12:15 PM
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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?
 
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Old 09-03-16, 12:30 PM
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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.
 
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Old 09-03-16, 12:58 PM
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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.
 
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Old 09-03-16, 02:25 PM
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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.
 
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Old 09-03-16, 04:23 PM
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You may find it hard to fit a gfi in the older small boxes. A gfi breaker can be used.
 
 

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