Add grounding bar or combine grounds?


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Old 06-19-04, 08:04 PM
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Add grounding bar or combine grounds?

I have 100 amp service in a Siemens panel. There is no separate ground bar, so both neutral and grounds are connected to the neutal bus. My problem is that I'm running out of space on the bar yet I've two circuits to still run. I was planning on combining several of the 20 A grounds and connecting them to the bus bar with a lug (twist all wires together and secure them with the lug), however when I went to the store to buy the part I needed, the guy working there suggested I add a ground bar instead. I realize I'd need a jumper to connect this new bar to the neutral that is currently grounded, but I'm not sure if adding a ground bar is necessary.

Which option is preferred? I only need to free up about 4 spaces and I'm concerned that the panel may become to crowded if I add the new ground bus.

What do ya think?
 

Last edited by LSummers; 06-19-04 at 08:07 PM. Reason: clarification
  #2  
Old 06-20-04, 02:37 AM
doingitmyself
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Does the neutral bus have a bond to the panel cabinet? It needs to have one.

I'd install a separate ground bar, and separate the grounds from the neutrals (put all the neutrals on the neutral bus and the grounds on the ground bus), and bond the ground bus to the neutral bus, if this is the main service entrance. If this is a subpanel, other factors are involved!

I think it's permissible to have the grounds and neutrals on the same neutral bus if the neutral bus is bonded to the panel cabinet. Only one neutral per screw lug, but you can, I believe, place two ground wores under the same screw - this might free up some space.

Still, best, I think, is to install the ground bus and go from there. Wait, however, on the pro advice.
 
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Old 06-20-04, 07:55 AM
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Thanks for the input.
The nuetral bar is bonded and currently both of the panel grounds are attached to it. If I go the route of adding a separate ground bar, then I will need to use a #4 copper Bonding Jumper from the existing nuetral to the new ground bar and then transfer both of the panel grounds to the new ground bar. Then all of the grounds would need to be moved to the new ground bar. Is this correct?
 
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Old 06-20-04, 08:05 AM
J
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You don't need to move all the grounding wires. You can connect neutrals and grounding wires to whichever bar is more convenient. Install the grounding bar.
 
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Old 06-21-04, 06:45 AM
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Thanks guys, I'll go ahead and do it. I figured this was probably the way to go, since it involved more work. But really, what's a couple extra steps when it comes to electrical and doing it right?

Thanks again!
 
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Old 06-21-04, 06:53 AM
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Originally Posted by John Nelson
You don't need to move all the grounding wires. You can connect neutrals and grounding wires to whichever bar is more convenient. Install the grounding bar.
To expand on John's reply let me point out that the new ground bar will be bonded to the cabinet of the panel by it's mounting screws and the factory installed neutral buss should be bonded to the cabinet by a green screw or a conductive metal strap that is commonly called the noodle. Since both buss bars are bonded to the metal cabinet they are bonded to each other.

The markings in your panel assembly should indicate how many conductors each terminal can accommodate. In many panels you can terminate two Equipment Grounding Conductors that are the same size in a single terminal hole of the bonded neutral buss bar. In all cases you must not terminate more than one current carrying conductor to the same terminal of the buss bar. That is because the current carrying conductors expand and contract as the load on them increases or decreases. Since that expansion and contraction will not be the same on both current carrying conductors the connection would gradually loosen under the influence of the thermal cycling of the conductor.
--
Tom Horne
 
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Old 06-21-04, 08:28 AM
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Got it. So do agree that I should add the new grounding bar or terminate two grounding conductors in the same terminal hole (if my panel allows for this of course) in order to free up space?
 
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Old 06-21-04, 10:19 AM
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Yes, either would be a perfectly acceptable way to proceed.
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Tom H
 
 

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