Electrical Pannels

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  #1  
Old 11-16-05, 08:48 AM
Joe510
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Question Electrical Pannels

It is my understanding that when wiring a load center you need to bond the netural and ground.
It is also my understanding that when wiring a sub pannel you do not bond the netural and ground.
What is the reason, purpose, and or danger these two situations are done differently?
 
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Old 11-16-05, 08:55 AM
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The rules aren't quite as simple as you presented them, but you have the basic idea. The motivation for the rules are to prevent current from flowing on grounding wires except in fault conditions.
 
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Old 11-16-05, 01:02 PM
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A "Load-center" is a "trade-name" for a residential panel. A "sub-panel" is a panel that is physically seperate from the Service-panel, and located at a certain distance from the Service-panel; the distance could be 12" or 12 ft

A "load-center" equipped with a "Main-breaker" could be used either as a Service-panel or as a sub-panel.

The ONLY point where the Neutral ( White wire) is Ground-connected is in the enclosure that contains the Service Dis-connecting means. Any and all Neutral conductors that extend from the enclosure that contains the Service Dis-connect are required to be Ground-isolated at all termination-points beyond the enclosure.
 
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Old 11-16-05, 07:49 PM
Joe510
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service pannel/ sub pannel

This is the first time I have used this I hope this reply gets back to both pattbaa and John. Thanks for the reply, I think I see now, if you loose a netural contact at your sub pannel, you may have current returning to your service pannel, switch or receptical on a ground wire.
 
  #5  
Old 11-16-05, 07:53 PM
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You don't even need a loose neutral to create the problem. If the grounding wire and neutral wire are bonded in a subpanel, current will flow back to the main panel on both (about half and half if the wires are the same gauge). This is bad.
 
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