Extending Ungrounded Cable

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Old 09-09-18, 03:54 PM
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Extending Ungrounded Cable

Seperated from: https://www.doityourself.com/forum/e...conductor.html

I have a 1960's era room which was added on to a 1950's era house. Inside there is a 1 gang metal receptacle which is powered via a 12/3 Romex which has a white, black, and red wire. There is no ground wire but the red is attached to the ground screw. They used to sell 3 wire Romex without a dedicated grounding wire and it appears that they might have simply used the red wire as a ground. I want to connect to this a GFCI receptical on the exterior side of the wall. Please advise.
 

Last edited by ray2047; 09-09-18 at 04:15 PM.
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Old 09-09-18, 04:20 PM
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Ungrounded cables can not be extended. Grounds #6 and smaller must be factory green. Other colors can't be used.
 
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Old 09-09-18, 04:28 PM
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Electricity doesn't know the color so let's pretend that it's green. . How can I test if the red wire is performing the grounding function?
 
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Old 09-09-18, 04:35 PM
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To answer your question directly.....you can measure from black to red and you should measure 120vAC.
 
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Old 09-09-18, 05:16 PM
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Measuring across black to red lit up the 110v light on my probe so I can assume it's grounded and it would support running an additional exterior GFCI receptacle?
 
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Old 09-09-18, 06:52 PM
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#1, Use a real volt/OHM meter not a trouble light!
 
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Old 09-09-18, 07:04 PM
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A GFCI does not need a ground in order to function.
 
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Old 09-09-18, 07:05 PM
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You don't need a ground for a GFCI to work but using the red is a code violation. 110v is low but acceptable. Usually it should be close to 120v.
 
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Old 09-09-18, 07:07 PM
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OK, my meter measures 121.9
 
 

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