Grounding an ungrounded box

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Old 03-22-20, 10:14 AM
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Question Grounding an ungrounded box

I have a house built in the late 50's all of the outlet boxes are metal and the wire in the box consists of a hot and neutral. I recently replaced the old 2 prong outlets with new 3 prong. I attached the ground from the outlet to a screw in the box. When testing the outlet with a plugin tester an open ground is indicated. I know from past remodel work that the boxes have a copper wire wrapped under a nail that secures the box to the stud. This wire runs from the sub panel continuously to all boxes. If this ground wire is broken or open what is the best way to reground the outlet boxes that complies with code?
 

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03-22-20, 10:16 AM
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Welcome to the forums.

If your older home only has two wire cable with no ground wire then there is no ground at that device. That means you can only replace the original receptacle with a two slot receptacle or a GFI receptacle which doesn't require the ground to protect from ground faults.
 
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Old 03-22-20, 10:16 AM
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Welcome to the forums.

If your older home only has two wire cable with no ground wire then there is no ground at that device. That means you can only replace the original receptacle with a two slot receptacle or a GFI receptacle which doesn't require the ground to protect from ground faults.
 
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Old 03-22-20, 11:01 AM
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Some old houses are like yours with an unused grounding conductor. It is usually reduced size so doesn't meet today's code. Sometimes the wire is cut off as the installers didn't know what to do with it. Having the wire under a nail doesn't work as you are finding.

In addition to options mentioned above, you are permitted to run a wire back to the panel or "An equipment grounding conductor that is part of another branch circuit that originates from the enclosure where the branch circuit for the receptacle or branch circuit originates" along with several other options. It is not commonly done as most say to run a new cable if you are going to be running a new wire anyway.
 
 

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