Help with main and sub panel ground connections

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  #1  
Old 11-13-14, 10:58 AM
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Question Help with main and sub panel ground connections

Hi -I recently upgrade my service from 100A to 200A. I had the inspector come out yesterday and he needed me to make a few changes. He said that my ground coming from my subpanel inside needed to go through the same raceway (PVC) to the grounding rod outside. He did comment that there was no way that I was going to be able to fit my ground through the PVC. Right now it's just stapled up next do the PVC. He also said that I needed to run another #4 ground from my main panel outside to my water main inside. I did make this change. I am hoping someone can review exactly what I have in place and let me know if this looks good or if anything seems to be wrong. I don't want to have him come back and tell me it's still wrong.

Main shut off panel is outside. From here, I have a #4 going from this panel down to the grounding rod. I also have a #4 going from here into the house and to the water shut off, jumping the meter.

I then have a sub panel inside. In this panel, I have a #4 going from this panel outside directly to the grounding rod.

Attached are some photos to help give a visual. There is also an old ground #6 or so I'm guessing in the sub-panel going to the water. This was from the old 100A box and I just left it in place and connected it to the ground bar in my sub panel. I figured it couldn't hurt having it but will remove it if necessary.

Thank you!
 
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  #2  
Old 11-13-14, 11:18 AM
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I then have a sub panel inside. In this panel, I have a #4 going from this panel outside directly to the grounding rod.
Under NEC guide lines no ground wire is required for a subpanel in the same structure. Is this a local code variation? The sub panel does require an equipment ground between the first panel and the subpanel but that connects to the ground bar in your panel. I can't tell from the subpanel picture do you have an isolated neutral bar and a separate bonded ground bar?

 
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Old 11-13-14, 12:54 PM
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Hi, thanks for the reply. It's very possible that I misunderstood exactly what he was telling me. Unfortunately I'm not familiar enough with ground codes as I should be and could have misunderstood him. There are no local code variations, it's strictly NEC. I'm on 2011 since I pulled my permit in February.

Correct, ground and neutral bars in the sub panel are separate.

The ground from this sub panel is going out to the rod, but if I'm understanding you correctly it should be connecting to the main panel instead? This could be why the inspector was confused, since the ground isn't going through the PVC along with the 3 other feed wires he could have missed that it wasn't connected to the main panel.

Here is another picture of the sub, zoomed in a little and saved higher res..
hopefully this helps. https://www.dropbox.com/s/xjanqso5qr...panel.jpg?dl=0

Thanks again, I really appreciate any help!
 
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Old 11-13-14, 01:09 PM
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The ground from this sub panel is going out to the rod, but if I'm understanding you correctly it should be connecting to the main panel instead?
Yes, that is correct assuming in the same building. I see two neutral bars but no ground bar in the panel. Neutral bars are on insulators, ground bars are connected directly to the case.

However some manufactures allow you to use one neutral bar as a ground bar in a subpanel by installing the bond strap or bond screw and the other neutral bar as a subpanel neutral bar by removing the bond strap or screw..
 
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Old 11-13-14, 01:49 PM
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Good point on the ground bar not having a strap or screw. I'll have to look to see if I have either.

Just so I'm 100% clear on what I need, would you mind please confirming this is correct? Sorry that I need it in laymens terms

Sub panel:
A) #4 from the ground bar in subpanel connected to the main panel. This would be the only ground wire needed in the subpanel.

Main panel:
A) #4 from main panel to the water main inside of the house (Jumping the meter)
B) #4 from main panel to grounding rod. Comcast ground wire is also connected to this using a bonding bridge
 
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Old 11-13-14, 03:26 PM
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A) #4 from the ground bar in subpanel connected to the main panel. This would be the only ground wire needed in the subpanel.
Yes, except of course the branch circuit grounds all of which must go to the ground bar. Yes, and remember the neutral bar must be bonded (exact opposite of subpanel).
 
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Old 11-14-14, 01:02 PM
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Thanks again. I made the changes last night with the sub ground wire and got it removed from the rod and connected to the main box (Which is bonded with the netural).

I also verified that I do have the green bonding screw in the sub panel. I forgot since it was one of the first things I did and it was hard to see without pushing wires out of the way.

My last question is this. Since I didn't run the ground from the sub panel to the main panel within the PVC with the hot and netural wire, do I have any options to correct this? The inspector pointed this out and he even commented that there was no way I was going to get it into there now. It didn't sound like he was going to make me re-run with the ground included, but you never know. Right now it's ran along the PVC and stapled right below it. Is there anything else I should do for this or just keep it as is and hope he doesn't make me correct it? I know code says they all need to go through the same raceway, but I don't know the technical reason for this and if there is a safety hazard having it done the way I have it.
 
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Old 11-14-14, 01:16 PM
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I also verified that I do have the green bonding screw in the sub panel.
That must be removed fro the neutral bar in the subpanel. I still think you are confused about wiring the subpanel. You must have an isolated neutral bar. Only the ground bar is bonded.
I know code says they[ground] all need to go through the same raceway,
Actually no only the current carrying conductors need to be in the same raceway according to the NEC but your inspector trumps the NEC. If he says he wants the ground in the same raceway then they must be.
 
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Old 11-14-14, 01:44 PM
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What size conduit did you run between panels? It may be a pain but you should be able to pull the grounding conductor into the conduit.
 
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Old 11-14-14, 02:55 PM
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It's a little over a 25 foot run between panels. I had a h*ll of a time pulling the 3 wires, which are 3/0 cables and are running through 1 1/2" PVC. Not saying it's impossible, but trying to now get a #4 ground through there would be nearly impossible. There is also a pull 90 PVC box on the outside that brings the wire up into the main box and then inside there is the curved PVC end that connects into to the sub panel. I think the only possible way I could do it is if I were to completely re-do that whole run, which would not be fun. I'd definitely go 2" instead of 1 1/2" if I had to do it again. I guess I'll just wait and see what he says. Hopefully he's willing to make some type of exception. If I have to do it then I have to do it. I was just hoping maybe there is some other option I could offer to him to see if that would be acceptable. This is my first time doing this much work and going through an inspection so I don't know what to expect as to what type of things they can typically let slide, etc.
 
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Old 11-14-14, 03:05 PM
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Hi Ray - I apologize, I may be confused or perhaps just using the wrong terms.

On the right hand side of the subpanel, I have the neutral bar with only the neutrals connected to it. The box came with a bar at the bottom connecting both sides, but I removed this since it is a sub panel.

On the left hand side, there is another bar that looks similar to the neutral bar, but it has all of my grounds connected to it. In this bar, there is a green screw that goes through the panel itself.

Perhaps the inspector is confused himself. He quoted to me "300.5 All conductors in same raceway or trench" . From what I can tell, this only applies to underground installations. My installation is definitely not underground by any means.
 
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Old 11-14-14, 03:08 PM
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Yikes, you're already too full on that 1-1/2" pipe with just the three conductors - no wonder it was so hard to pull through such a short run. A 25' run shouldn't be that big of a hassle.

The only good solution I see is to pull out your wires (hopefully intact), demo out what you've got and replace with 2" pipe. Best case is that the wires weren't damaged on the pull in, and make it out clean as well. You could thin out some wire lube with a little water and blow it through the pipe with an air compressor or shop vac to help extract the wires.

The only situation I can think of for a ground not in the same pipe as the hots would be retrofitting a old ungrounded building; and even that would be sketchy on the panel feeders. I really don't see the inspector approving that installation.
 
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Old 11-14-14, 03:09 PM
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All conductors does not just apply to underground but to all applications.
 
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Old 11-14-14, 04:04 PM
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Understood. I was just confused about the underground thing since he stated 300.5 which only talks about underground wire. 300.3(B) states all conductors including grounding must be in the same raceway... so perhaps that's what he meant
 
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Old 11-14-14, 04:12 PM
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Thanks. Sounds like that is going to be my best options. Hopefully I can salvage the wire, but if not I'm going to run 2/0 instead of 3 which will help as well.

Another question regarding the same code. The previous wiring had underground wiring going to my detached garage. The problem was that it was 2 circuits/cables and each cable only had 2 conductors, no ground. Current code says I can only run a single circuit to the garage. Instead of ripping out all of the old wire and digging a new trench, etc. I used the 2 existing wires and basically combined them into a 14/2 with 1 wire not being used. I have a 14/2 wire feeding the junction box from my panel and then another box in the garage with a single 14/2 coming out feeding the garage.

Reading the code it states that all conductors must be in the same cable, so I'm guessing technically this is not OK either.

Any thoughts on this? The inspector hasn't gotten to this circuit yet but now I'm nervous about this one too. Is it common/OK to explain your case and ask them to make an exception or do you just do as they say?
 
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Old 11-14-14, 05:26 PM
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Your garage is not code compliant. You could run 12-3 from either two handle tied single pole breakers or one two pole breaker (called a multiwie circuit). That would provide you with two 20 amp 120 volt circuits and would be code compliant. Note if you are supplying the subpanel from a 100 amp breaker. the EGC only needs to be #8 (Cu).
 
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Old 11-14-14, 08:07 PM
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It's a little over a 25 foot run between panels. I had a h*ll of a time pulling the 3 wires, which are 3/0 cables and are running through 1 1/2" PVC.
You have a mess. You should have come here before you started this project.
 
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Old 11-14-14, 11:47 PM
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Reading the code it states that all conductors must be in the same cable, so I'm guessing technically this is not OK either.
No, it's not OK. I would also venture a guess that the ungrounded, underground wiring is far beyond its useful age too. Anything that old has some type of natural rubber insulation and is certainly rotten by now.

Any thoughts on this? The inspector hasn't gotten to this circuit yet but now I'm nervous about this one too.
It should be replaced or disconnected until it can be done right.

Is it common/OK to explain your case and ask them to make an exception or do you just do as they say?
It's common to ask I'm sure, but in this case an exception does not make sense. The inspector can't just waive the code as it is his job to make sure the job is done correctly. He could (and should) get in trouble for that. He needs a good justification to grant an exception, and in many areas it would also require agreement from the chief inspector (his boss).
 
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Old 11-17-14, 08:25 PM
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Thanks for all of the help. Garage is going to have to wait until spring comes along. I'm just going to disconnect it for now and deal with it later.

I did get the main->sub panel connection re-done. Was a fun weekend project. I ripped out all of the old 3/0 wire and will sell it to the recyclers. I also took down most of the 1.5" PVC and replaced it with 2". The only spot that I kept the 1.5" was at the end right before the elbow that connects into the subpanel. Changing that to a 2" would have made me physically change how the panel is mounted and I didn't want to do that. I ran new 2/0 wire through, including the #4 ground. The elbow was a bit of a challenge but I eventually got it pulled through.

It's all up and running, inspection is set for tomorrow.
 
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Old 11-17-14, 09:07 PM
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including the #4 ground
You missed where I said the ground could be #8 didn't you.
 
  #21  
Old 11-18-14, 11:08 AM
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Hi Ray - I was referring to the main -> sub panel in the house which is 200A. I didn't do anything with the garage other than disconnect it. Once spring comes around I'll get a trench dug and add the sub panel out there.

Good news is the inspector just left and I passed with flying colors! So, thanks again for your help. Now, onto the next project... adding blow-in fiberglass to the attic.
 
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