metal box grounding


  #1  
Old 01-19-08, 04:58 PM
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metal box grounding

Why can't you ground a switch with the ground wires in a metal box? Why do you have to ground to the box? The ground wires go to ground either way, don't they? I changed a switch in my house and ran the bare copper ground to the switch instead of to the box and it wouldn't work, also a switch and outlet downstream wouldn't work either, is this right? The house is 30 yrs. old, and has romex wire.
 
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Old 01-19-08, 05:23 PM
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Sometihng else is wrong. You must ground the switch and the metal box together. All the metal parts in the box should be connected together with the ground wires..
 
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Old 01-28-08, 09:20 PM
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Originally Posted by handy39
Why can't you ground a switch with the ground wires in a metal box? Why do you have to ground to the box? The ground wires go to ground either way, don't they? I changed a switch in my house and ran the bare copper ground to the switch instead of to the box and it wouldn't work, also a switch and outlet downstream wouldn't work either, is this right? The house is 30 yrs. old, and has romex wire.
Let say you loss the ground at the switch, and the hot wire was touching the box. Now the box is energize, you touch the box and someway you was grounded. Now you complete the circuit. That why you ground the box and switch or receptacle. This keep you from getting electocute
 
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Old 01-28-08, 09:30 PM
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The ground wire is landed first at the box then to the switch or repectale next on metal box.


now this part you mention that the switch dont work what kind of old switch it was before and how it hook up ??

if you do used the ground wire as traviller this is a very illegal setup.

please reply to us how you got the old switch hook up and how many wire in the box ?/

Merci, Marc
 
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Old 01-28-08, 11:35 PM
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Never thought about it before, but is it true, then, that you cannot have a switch loop w/ a metal box since there is no ground wire?
 
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Old 01-29-08, 04:17 AM
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Yes, a switch loop has a ground wire. You can no longer buy NM cable (in typical sizes for branch circuits) that does not have a ground wire.
 
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Old 01-29-08, 04:24 AM
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Originally Posted by DavidT
Never thought about it before, but is it true, then, that you cannot have a switch loop w/ a metal box since there is no ground wire?
Assuming you are using modern NM-B cable of course there is a ground wire. If you were referring to French277V's post he was writing about using two conductor NM on a three way switch where you should use 3 conductor and using the ground instead as the third conductor.
 
 

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