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Grounding With Metal Boxes

5K views 20 replies 9 participants last post by  jbfan 
#1 ·
How do you guys do your ground? I've seen this a few times with metal boxes. They say you can ground on the wire nuts like that and then when the metal outlet tabs and screws are screwed into the metal box that it grounds itself without using the ground screw on the outlet and in the box. What are the pros/cons of this?

 
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#11 ·
Probably 40 years ago or more.

The sheath must extend into the box at least 1/4". All grounds need to be connected together and to the box and device.
 
#13 ·
Yes it is sloppy, but let's back up for a second. My entire house was grounded in a similar manner. House was built in 1959, I a guessing that the technique of wrapping wire around a screw on the outside of a metal box was pretty typical in 1959. And the technique likely violates current NEC requirements, since the grounding wire is apparently supposed to be connected to a green grounding screw inside the box. But the technique certainly works electrically, since the copper grounding wire is mechanically connected to the box.

Assuming the outlet grounding wire is connected to a grounding screw inside the box via a pigtail, the system is electrically grounded. I would class this as a technical violation of NEC, and if the wire was installed some years ago, it may have been compliant with regulations at the time, in which case it may be grandfathered. Is it worth fixing? Probably, but does not look like a really high priority. If the outlet is ungrounded, that is a more serious problem, but you can't tell from the photo.
 
#16 ·
I just want to prove a point to someone. I think we agree it isn't up to code and not the proper way, but why is it not ok? What is the problem with it? There are probably millions of houses grounded this way. Ignore that the wire should be further in the box, that's a given.
 
#21 ·
If the washers were not removed from the receptacle, then it is not grounded properly anyway.
With a loose ground connection, a high current fault could sit there and arc, creating a fire.
Just because they did it that way years ago, does not mean it was safe then.
 
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