Sub Panel

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Old 01-30-02, 10:05 PM
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Sub Panel

250AMP main panel, 100AMP subpanel 15 feet away interconnected with #4 wire.
New code requires segrigation of neutrals to one buss bar and grounds to the other on the sub panel.
Main panel buss bar's are mixed with neutrals and grounds. Should the main panel buss bars be segregated to match the sub panel?
 
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Old 01-31-02, 06:59 AM
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Not a new requirement. Main panel should have neutral and ground bonded (connected) together, not sub-panels. Generally, in residential applications, no where else should the neutral and ground touch each other.
 
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Old 01-31-02, 09:54 PM
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Question Sub Panel

Handyman.
First thank you for the reply and please forgive my ignorance but I do not understand?
My main panel has two buss bars that are mixed with neutral (white) wires and ground (bare copper) wires.
Ive added a sub panel, 100amp and it only had one buss bar for neutrals and ground wires.
The inspector told me I had to add another buss bar and tie the ground wires to one bar and the neutrals to the other bar., which I did.
So I was wondering if I needed to rewire the main panel so that the ground wires and the neutral wires were on there own buss bar like the sub panel instead of the way they are now, neutrals and grounds together on two buss bars.
Ill be using a #4/3 with ground to connect the main panel to the sub panel.
 
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Old 01-31-02, 10:06 PM
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Oops

Sorry I ment HandyRon not Handyman a written.
 
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Old 02-01-02, 12:34 AM
joeh20
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sub panel

No, you don't have to rewire the main panel. The neutral bar in the main panel should be bonded to the box itself. There should be a green screw threaded into the neutral buss in to a threaded hole in the box, it be a small lug screwed to the box and tightened under a screw in the neutral buss. This grounds your main neutral buss to your ground buss,box,conduit and main bonding wire going to the ground rod. This is to help the utility with a return path for their grid. But in your subpanel your neutral buss should be isolated from the box and all grounds, the reason being is that if your ground should fail at the main box your subpanel won't have to carry the whole load of the neutral conductors. Your neutral conductors in your subpanel aren't large enough to perform this on their own and shouldn't be expected to. I hope I explained this right, I am not a codes expert but I feel I am a competent part time electrican.
 
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Old 02-01-02, 10:19 AM
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HandyRon is correct but I would like to clarify.

1. Subpanels located inside a dwelling require a grounded (neutral) and equipment ground.
2. The grounded (neutral) and equipment ground are bonded (joined together) at the service panel.
3. The grounded (neutral) is isolated from the subpanel enclosure (we call it floated).
4. The equipment ground is bonded to the subpanel enclosure.
This prevents a parallel current path on the grounded (neutral) and equipment ground back to the service panel. Only the neutral should carry the current back under normal operation. The equipment ground carries fault-current back to the service panel.
 
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Old 02-01-02, 10:34 AM
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You said "The inspector told me I had to add another buss bar and tie the ground wires to one bar and the neutrals to the other bar., which I did.".

He/she was right to ask you to add an extra termination bar, but be sure, in the sub panel, that the neutral termination bus is not touching (isolated electrically) the box or ground. The reference by other posters of grounded conductor is correct although confusing to the layperson. Grounded conductor, as illustrated by thinman is the neutral, not the equipemnt ground (or just ground).
 
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Old 02-01-02, 09:45 PM
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Thank You

Wow this site is great you all ya'lls help is greatly appreciated
 
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