Sub Panel jumpers

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  #1  
Old 04-16-10, 09:34 PM
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Sub Panel jumpers

I have successfully installed a sub-panel with the help of many people on this forum. The inspector was surprised at the quality level and degree of professionalism and attention to detail that I put into the sub panel. Thanks to all.

Now I am getting ready to start moving circuits over to the sub panel. Many of the circuits do not have enough wire to go directly to the newly installed sub panel. So I will install jumpers from the existing service panel to the new sub panel and new breakers.

My question is this: Does the ground wire have to go over to the sub panel or can it remain grounded in the exisiting service panel?

I understand that the neutral MUST be installed in the new sub panel and it MUST be in the same conduit as the hot wire. This is due to Physics and electrical fields that I know nothing about. I just know it is required.
 
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  #2  
Old 04-17-10, 04:49 AM
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good morning. Is there anyone on this forum that can answer my question?

Do I need to jump the ground wire from my service panel back to the sub panel or can the ground stay connected to the graound bar in the service panel and the Hot/Neutral be jumpered back to the sub panel?
 
  #3  
Old 04-17-10, 05:20 AM
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Generally the ground wire needs to go with the circuit conductors. How is the sub connected? By short pipe and is it next to the main? I am not sure how a inspector feels about using the main as a Jbox here, ideally is to wait for Ipooks or one of the masters for this question, if the circuits were passing thru the main it likely wouldn't make much difference but one of the guys will know for sure.
 
  #4  
Old 04-17-10, 06:24 AM
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The sub is connected to the main with 1" sch 40 PVC. There are only 4 conductors (H/H/N/G) in the 1" raceway. I have installed 3/4" Smurf tube between the panels for adding the jumpers.

The inspector said that it is acceptable to use the main service panel as a Jbox as well. Although I would be willing to install a large JBox and run the circuits through the Jbox instead of main service panel.

I prefer to do it right rather than cheap or less time. Even if using the main panel IS acceptable per NEC but it is BETTER to install a large Jbox then I will take the better (jbox) route. However, if it is acceptable and widely used practice of using the main as the jbox, then I will proceed.

Sometimes even the inspectors get it wrong....that's why I'm here. )
 
  #5  
Old 04-17-10, 09:05 AM
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Now I have 2 questions"

1) Original question: When extending a branch through the main panel and into the sub panel, does the ground have to be disconnected from the main panel ground bar and connected to the sub panel ground bar? If the bare ground wire is required to go along with the H/N conductors then can I use a Non-green wire nut?

2) How is the "box fill" calculations performed in a service panel? I will extend about 10 circuits over to the sub panel using wire nuts AND tape (yes I said it, I like to use tape with my wire nuts). So how many is TOO many? or better yet what is the calculation?

My inspector seems to be a "good guy and reasonable" but says things like "it needs to be secure" and "more than finger tight". Whatever any of that means. So Im sure he will say that a "few wirenuts inside the main service panel is acceptable but not too many". So I want to do it right but also get approval as well.
 
  #6  
Old 04-17-10, 09:36 AM
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Since the boxes are connected with PVC, I would say you should extend the grounds into the sub. If it was a short rigid nipple, I don't think it would be a problem to terminate them in the main as they would essentially be one box electrically. Maybe it's not an issue anyway -- I can't think of a specific code to allow or forbid it.

Using the main as a j-box is just fine for an application like this. It is very common.

Any color wirenuts are fine; the green ones are just a market thing.

I have never done or considered a box fill on a main panel, so I don't think it's an issue. It's pretty common to move 6, 8 or 10 circuits over to a sub when you install something like a generator transfer panel so you certainly won't be the first to do it.
 
  #7  
Old 04-17-10, 10:57 AM
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If it was a short rigid nipple, I don't think it would be a problem to terminate them in the main as they would essentially be one box electrically. Maybe it's not an issue anyway -- I can't think of a specific code to allow or forbid it.
Thats kind of what my take on it was but didn't want to write it in stone without second qualified opinion. If it was an issue of crowding the pipe going to the sub I would leave them at the main, probably would as thats where they terminate in the end anyway.
 
  #8  
Old 04-17-10, 03:27 PM
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Be sure that the neutral is not bonded to ground in the subpanel.
 
  #9  
Old 04-18-10, 12:08 PM
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"My question is this: Does the ground wire have to go over to the sub panel or can it remain grounded in the exisiting service panel? "

If you are referring to the Service Grounding Electrode Conductor , it must remain connected to the Service Neutral terminal block in the Service panel.

The best possible installation for wiring panels is to have terminal connections only inside the panel , and with each conductor under it's own terminal.

A 4" square wireway is an ideal enclosure for conductor splices where many cables / raceways for Branch -Circuit conductors are involved. The lenth is proportional to the number of cables / RW's.
 
  #10  
Old 04-19-10, 07:58 PM
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PATTBAA: I was referring to the branch circut grounding bare wire. I am transferring over circuts from the main service panel to the generator sub panel.

IBPooks answered my questions. I will add a jumpers for all three wires (H/N/G) and terminate them in the new sub panel. I will use caution to ensure the connectors are properly installed and not "crowd" the main service panel. Oh, and I will use tape. I know this is a sore issue for many professionals but who else will buy this tape and keep Americans employeed???? hehe

I did not know that the green connector is a marketing ploy. I guess I never really thought of it. I "assumed" that all grounds were requried to be green. There I go making an @ss out of myself.....again. I wonder if that is why my wife left me????? Hmmmm.

Anyway, thanks again for the input from everyone.
 
  #11  
Old 04-20-10, 01:14 AM
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I wonder if that is why my wife left me????? Hmmmm.
The greatest moment of my life was when my wife left me. Beer 4U2
 
  #12  
Old 04-20-10, 12:38 PM
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furd: I would agree with you. However, I had dinner with my ex and it looks like she is coming home. I told her that I really like the single life but she insisted.

She said, "I have been thinking lately (that's a first). I think that 25 years is a long time to throw away. But, you will have to stay off the internet and spend more time with me."

I told her that she was crazy. She is really a wonderful person and a very good mother. So I might give it another shot. I have to get rid of the 2 girl friends though. That might be a little tough to do but I will see what happens. It might work out.
 
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