Bonding of neutral bar

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  #1  
Old 09-14-05, 01:23 PM
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Bonding of neutral bar

I was in Lowes this morning looking at a Square D 125 amp service panel.

The ground and neutral are separate. There is a large green screw in the package. The instruction say to use this if the neutral bar is to be bonded to the panel. Should the nuetral bar be bonded to the service panel?
 
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Old 09-14-05, 01:49 PM
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If this panel is the main panel for the house, then the neutral and grounds should be bonded with the provided screw. This only applies to the main panel which houses the main disconnect for an electrical service.

If this panel is used as a subpanel, the neutral and ground should be isolated; remove the bonding screw and throw it away.

The only exception is for a three conductor fed subpanel in a detached outbuilding. This situation is rare and ill-advised.
 
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Old 09-14-05, 01:53 PM
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This is a sub panel located inside the garage approximately 4 feet from the main panel.

Toss the green screw.

Thanks
 
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Old 09-14-05, 02:00 PM
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In the setup you describe, you need four wires between the main panel and the sub panel you will be installing. Two hot wires, a neutral wire and a ground wire.
 
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Old 09-14-05, 04:15 PM
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Got it. Thanks for all the help
 
  #6  
Old 10-03-05, 08:02 AM
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If you throw away the green screw, how is the sub-panel cabinet grounded? The panels I use have a removable bus bar between the neutral and ground bus. You remove the bus bar but you still need to ground the sub-panel itself.
 
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Old 10-03-05, 08:07 AM
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You throw away the green screw so that the neutral bar is not electrically connected to the panel. The panel is grounded by the ground bar.

If your panel comes with two bars where one is designed as a neutral or ground/neutral, and the other is a ground only then it is important to break the connection between them and make sure that the bars are isolated.
 
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Old 10-03-05, 08:11 AM
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Yes, but both busses "float". Once you isolate them by removing the tie bar, you still need the green screw to bond the ground bus to the cabinet. The reason they leave it out is so that you can select which to use as the neutral bus and which to use as a ground bus.
 
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Old 10-03-05, 08:15 AM
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Many panels come with one bar. That bar has a green screw to make the bond. With these panels you throw away the green screw if you need the bar to be a neutral only bar, and then add a ground bar.

If you have a different panel that has two bars then you need to follow the instructions for that panel so that one becomes a ground bar and the other a neutral bar.
 
  #10  
Old 10-03-05, 08:24 AM
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I suggest this method----expose the metallic surface of the enclosure by removing the paint, and "Bond" a lug to the exposed metal with a fastener----pass the Equiptment Grounding Conductor first thru the lug, and then to it's termination-point on the Grounding terminal strip---next,----

Good Luck, & Learn & Enjoy from the Experience!!!!!!!
 
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Old 10-03-05, 08:40 AM
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My point was that gmasingale stated that the panel he was considering had separate ground and neutral busses. Since the manufacturer (Square D) leaves it up to the installer to determine which bus to select as ground and which bus for neutral, you're still going to NEED the green screw and you should not throw it away. And should you get a panel that would require the purchase of a separate bus to use for ground, you're still going to need the green screw. I've read in this forum many times to "throw away the green screw" when referring to sub-panels. But I wonder if that suggestion had the proper caveats.
 
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Old 10-03-05, 11:43 AM
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Square D uses a separate ground bar that has the mounting screws contained in the package with the bar. There is no need for the green bond screw to mount this bar, and it would not fit thru the holes anyway.

The buss that comes with the panel would be used as the neutral buss in a subpanel type of installation. The additional bar would be for the grounds.
 
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Old 10-04-05, 07:14 AM
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Originally Posted by alittle
If you throw away the green screw, how is the sub-panel cabinet grounded? The panels I use have a removable bus bar between the neutral and ground bus. You remove the bus bar but you still need to ground the sub-panel itself.
That is why you run a dedicated ground wire with the power/neutral feeders from the main panel. i.e. 4 wires two hots, a neutral, and a dedicated ground. Land all of the neutrals to the neutral bar and the grounds to the ground bar. Do not mix the neutrals/grounds on the bars. However, in your case remove the strap, and install the ground screw on the ground bus to bond the panel chassis itself.
 

Last edited by scott e.; 10-04-05 at 07:17 AM. Reason: added content
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