Brittle wire


Old 12-03-15, 11:09 AM
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Brittle wire

I replaced an outside receptacle with a new GFI. When I tightened a wire nut on the ground pigtail the wire broke. I tried again and the ground wire broke again. I ended up using a push in connector because I was running out of ground wire in the box.

The wire is Romex(?), probably from the 60's when the wiring was upgraded. The insulated conductors in the box are bright and solid but the ground wire is a bit discolored and seems to be brittle. There is no evidence of moisture in the box. The wiring inside the house is in good shape. I had a problem with a very short ground wire in an outside light so it's possible that wire had broken in the past.

Is it unusual for exposed copper wire to become embrittled? Should the wiring feeding outside fixtures be replaced?
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Old 12-03-15, 11:19 AM
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That is one of the problems with the 1950s and 1960s era Romex. The bare undersized ground wire (usually #16 or #18) is more susceptible to corrosion than the thicker insulated wire, and becomes brittle over time. You really just have to be careful with them and not manipulate them any more than necessary.
Old 12-03-15, 11:45 AM
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Copper work hardens and breaks. The more it is bend the closer it comes to failure. Other metals become softer and break.

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