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Old 10-03-2009, 06:51 PM   #1
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Main disconnect neutral wiring


I have a setup where the service disconnect consists of a 100A Murray box with a fused disconnect. The service entrance includes two hots and a stranded neutral, originating from the meter outside the house, and connected to the hot lugs on the Murray, with the neutral connected to the neutral bus. So far so good.

The main disconnect feeds two separate subpanels, one upstairs and one downstairs. The upstairs subpanel is fed using SE wire, two hots and a stranded neutral, plus a separate #6 Cu wire acting as the independent equipment ground. The #6 terminates on a grounding lug which is attached to the disconnect box using a grounding screw.

So here are the questions.

1. The stranded neutral from the subpanel is uninsulated within the disconnect box (the Murray box). The neutral is connected to the neutral bus bar in the Murray box. Is there any problem having an uninsulated neutral inside the main disconnect enclosure, or is this considered standard and acceptable practice?

2. The independent equipment ground is connected to a separate grounding lug (separate from the neutral bus bar). Is it necessary to have a jumper connecting the IEG lug to the neutral bus bar, or is the metal box considered to be an adequate grounding connection?

I appreciate any response. If necessary, I can post a picture, but hopefully the above describes my situation well enough.

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Old 10-03-2009, 08:54 PM   #2
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Main disconnect neutral wiring


It is fine having an uninsulated neutral.

When you have a "sub panel" the neutral and grounds must be seperated. You can't have the grounds and neutrals on the same bar.

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Old 10-04-2009, 11:55 AM   #3
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Main disconnect neutral wiring


Your panels inside should have been fed with a 4 wire feeder. Two insulated hots, an insulated neutral, and a ground.
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Old 10-04-2009, 12:43 PM   #4
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Main disconnect neutral wiring


Like Jim said. Both sub panel feeders are violations. You needed four wires to each sub panel unless they are fed with metal conduit. The conduit would/could serve as the ground, but the neutral must be insulated. It is a current carrying conductor. You also cannot use a separate wire for the ground. It must be included in the cable, not running alongside.
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Old 10-04-2009, 01:15 PM   #5
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Main disconnect neutral wiring


OK, that clarifies things. The subpanels are fed with four wires, two hots and a neutral inside the SE covering, and a separate #6 copper wire which is used as the IEG. This happened because when the house was originally wired in 1959, the standard of practice evidently was not to use an IEG, so the SE feed to the subpanels included only the hots and the neutral, which doubled as the ground wire. Subsequently, when the original fuse box was replaced with breakers, a separate wire (the #6 insulated copper) was used as the IEG, however it appears the original SE cable was retained.

So if I understand this correctly, there is a technical code violation because the IEG is not part of the cable. Is there a fix other than to run 4 wire cable to the subpanels?
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Old 10-04-2009, 02:36 PM   #6
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Main disconnect neutral wiring


Dan.,

The only legit way you can slove it by you have to replace with SER cable which it will have two hots netural plus bare grounding conductor and you will have to enlarge the hole little bigger in case.

And this what it look like

This is a copper verison but the Alum is simauir to this

Merci,Marc

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