neutral and ground in main panel--not connected?

Reply

  #1  
Old 08-01-08, 03:05 PM
H
Member
Thread Starter
Join Date: Jan 2004
Location: United States
Posts: 1,197
Received 0 Votes on 0 Posts
neutral and ground in main panel--not connected?

I have been reading some of the books suggested here (checked out wiring simplified and for pros by pros wiring a house from the library--both on NEC2005)

I just had new entrance put in. I have two 200amp panels. I have one meter (used to have 2!) The meter feeds two main disconnects via 2 SE wires (2 insulated conductors and one uninsulated conductor) from the two disconnects I have two SER wires, each with 3 insulated conductors and one uninsulated conductor. in each panel, the 3 insulated conductors attach to the two hot buses and the neutral bus and the uninsulated wire attaches to the ground bus. The neutral bus and the ground bus are NOT connected! The ground bus is attached (bolted) to the panel but the neutral bus is isolated. Everything I read says that they (neutral bus and ground bus) should connected to each other in main panel, but not in subpanel. But, none of what I read shows using SER 4 conductor wire, only SE 3 conductor.

I only have one grounding rod. the bare copper wire from it comes up and goes to one of the outside disconnects, with an acorn near here and another ground going to the other disconnect. Each disconnect has another bare copper ground wire coming out of it and they attach to each other and go along with the two SER cables to main circuit breaker panels. BUT, it does not enter or contact the panels. It goes past them and attaches to my water main (I don't have a meter inside so the main goes underground for a while. I geuss there is a meter somewhere but nothing above ground?) So, this all seems strange from my reading. Of note, when the electrician was starting the work, he asked me if the neutrals and grounds were separated and when I told him that they were, he seemed relieved. Is this all OK? I know an inspector was here, but I don't know what he looked at and I don't think he was here after the power company subcontractor did their work. He was here after the SER wire was run in prep for the changeover.

Bill
 
  #2  
Old 08-01-08, 03:25 PM
I
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,942
Received 44 Votes on 42 Posts
Are you certain the neutral and ground bars aren't bonded? Sometimes the bonding screw or strap which connects the neutral bus to the box is not entirely obvious.
 
  #3  
Old 08-01-08, 03:43 PM
D
Member
Join Date: Jul 2008
Location: USA
Posts: 376
Received 0 Votes on 0 Posts
Neutral and ground should only be connected in one place. Since you have two panels and SER cable was used. then it is possible they are bonded someplace before the panel. Maybe at the disconnect which makes sense since the ground wire enters there first.

They would not have bothered to use SER cable if they were not going to isolate neutral and ground. There must be a reason for it.

Can you look inside the disconnects?
 
  #4  
Old 08-01-08, 04:37 PM
W
Member
Join Date: Jun 2008
Location: Eastern Georgia
Posts: 486
Received 0 Votes on 0 Posts
Neutral and ground are bonded either in the meter or at the service disconect, in your case this is on the outside of the house. With the disconect being on the outside of the house your 200 amp panels are technically sub-panels, which is why they are fed with 4 wires and neutral is isolated from ground.
 
  #5  
Old 08-01-08, 09:24 PM
M
Banned. Rule And/Or Policy Violation
Join Date: Apr 2006
Location: Columbus, Ohio
Posts: 239
Received 0 Votes on 0 Posts
Originally Posted by wire twister View Post
With the disconect being on the outside of the house your 200 amp panels are technically sub-panels, which is why they are fed with 4 wires and neutral is isolated from ground.
Yep. That's what I've always been told as well. My apartment has the same setup. Every tenant has a ML panel with neutral and ground separated due to the disconnect under the quad meter pack.
 
  #6  
Old 08-01-08, 10:37 PM
H
Member
Thread Starter
Join Date: Jan 2004
Location: United States
Posts: 1,197
Received 0 Votes on 0 Posts
I suppose I could open to take a look inside main disconnects tomorrow. Here are some pics of what I have. outside and inside one of my circuit breaker boxes.









you can see the copper wire coming up from grounding rod on left. It goes into the left disconnect, but has acorn on it and a piece of wire goes into right disconnect. to the right of right disconnect, you can see the copper wire running with the SER wire. this goes to near my circuit breaker boxes but does not enter and attaches to water line. Note that it goes into right main disconnect but has acorns with wire also going to left main disconnect. So, is only one grounding rod considered adequate?

on the other shots of circuit breaker box, you can see my neutral bus bar on top. the grounding bus doesn't look like it was really part of the box and is just attached with a bolt to the box. shouldn't the box have been sanded to get good connection? use copper instead of steel bolt? This is the way it was, the electrician did not touch this at all.

I will have look inside disconnect tomorrow if possible. assuming the ground and neutral are bonded inside, I have question as to electrical path. Electricity takes the path of least resistance. so it enters panel via hot wires. goes through a circuit and comes back to panel via neutral. from panel it goes to disconnect. at disconnect, assuming neutral and ground are bonded, where does it go? could go to water main, to grounding rod, or to mast head neutral/ground? which has least resistance? am I missing something here? I guess to get better idea I would need to see how the meter area is wired as well as the disconnects. at mast head, there is only three conductors. at meter there are 2 sets of three conductor cable and from disconnects, there are 2 sets of 4 conductor cable.

bill

bill
 
  #7  
Old 08-01-08, 11:46 PM
F
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,495
Received 36 Votes on 28 Posts
I'm going to withhold comment on the "workmanship" of that installation...

I will comment on this:
Electricity takes the path of least resistance.
That statement is false. Electricity takes ALL paths, the resistance only controls the amperage in each parallel circuit.

...assuming neutral and ground are bonded, where does it go? could go to water main, to grounding rod, or to mast head neutral/ground? which has least resistance? am I missing something here?
Yes, my friend, you are missing quite a bit here. The electricity returns to its SOURCE and that source is NOT the earth or a water pipe. Ignoring for the moment that the electricity is "alternating" 60 times a second on BOTH the "hot" and the "neutral" conductors what a circuit really is at any instant in time is a loop from the source to the load and back to the source.

Grounding a system has nothing to do with the proper operation of a circuit. Grounding is done for several safety reasons but the electricity NEVER travels in "ground" conductors except under fault conditions.

One more thing; there are no "acorns" visible in your pictures. I think that what you are referring to as "acorns" are the split bolt connectors on the grounding electrode conductors.
 
  #8  
Old 08-02-08, 12:36 AM
S
Member
Join Date: Dec 2006
Location: orange county
Posts: 285
Received 0 Votes on 0 Posts
The ground bus bar in the main panel, definitely needs to be properly affixed to the panel housing "that's for sure". I am not an expert by any means, but I do read a lot of these posts. Everything, to me, (except for the ground bus bar) appears correct. Perhahps John Nelson and or French will be along soon.
 
  #9  
Old 08-02-08, 01:32 AM
D
Member
Join Date: Jul 2008
Location: USA
Posts: 376
Received 0 Votes on 0 Posts
What an ugly mess to have on the side of your house! Could have been done a lot neater. Did they even seal the entrance holes? Looks like they just punched a hole in the siding.

They could gave gone into the house through the back of the disconnect and avoided the SER loop on the outside.
 
  #10  
Old 08-02-08, 04:30 AM
S
Member
Join Date: Jul 2008
Posts: 47
Received 0 Votes on 0 Posts
I will have to comment on the workmanship of this service.Your electrician should be ashamed of himself! We are supposed to be proffesionals in this trade not only to provide a valuable service, but show a little pride in our skills. In my 19 years I have thankfully only run into a handful of knotheads that terrorize there jobs like that. Looking at that would give me cause for alarm as well. If he terrorized the service like that on the outside, I would hate to see what is behind the sheetrock. None the less, although ugly they usually end up working. This is his journeymans fault for allowing this to be okay. If they don't care about workmanship then they probably don't put much thought into what they are doing. With that said I wish I could tell you they have violated any codes in regards to your question about the isolated grounds and neutrals. When that service wire hits your disconnects from the meter, the disconnects are now considered the "main service". All grounding must be bonded together with the neutrals at this point. Any service panels after this point, whether it is your main service or not, is now considered a "sub-panel" and both the ground wires and neutral wires must be isolated from each other. Beause your disconnects are considered your main service, all grounding and bonding must be terminated at this point. This includes the ground rods, bonding the cold water side of plumbing usually at the water heater or where the water enters the building (unless your plumbing is plastic then this does not apply) and bonding the gas pipe. All of these terminations must be accessable so you may have a blank plate over where the gas is and a #4 bond wire where your pipes come out of the wall at your water heater with a bond clamp on the pipe. As far as the one ground rod, it is only legal to put one ground rod in the ground if you can prove that there is 25 ohms of resistance established and that can be only proved by using a meager. Since it is silly to go through all that trouble and expense 2 ground rods are always required. I am from Washigton state and using split bolts to ground the other disconnect is clearly a code violation. The disconnects must have seperate grounds although they come from the same ground rods. I have never worked as an electrician in any other state than mine, but I do know we all bound no matter where we live by the codes outlined in the National Electric Code book. He also needs to secure his flex within 8 inches of leaving any box or device and every 4 feet after that. I don't see any but 2 straps on the light gray flex and that is certainly not within parameters. This stuff is the electrical inspectors job and am blown away that he is allowing these clear violations to happen. It almost feels like he has never seen this job. I am embarrassed for your electrician, but want you to know that the vast majority of us have alot of pride in our work and demonstrate a high degree of proffessionalism in our trade. Anyway, hope this answers some of your questions.
 
  #11  
Old 08-02-08, 07:07 AM
C
Member
Join Date: Aug 2007
Posts: 130
Received 0 Votes on 0 Posts
I'm gonna make a few comments on the install also, here goes, is it ugly? Beauty is in the eye of the beholder.

Does it meet code? looks to be missing a few straps.

Other than that, the owner paid for what he got... its that simple, not everyone can afford a top notch install. I really dont see the fuss, I dont work like that, but then again, some people would find my prices too high to begin with to even get the job.
 
  #12  
Old 08-02-08, 08:37 AM
D
Member
Join Date: Jul 2008
Location: USA
Posts: 376
Received 0 Votes on 0 Posts
I am not sure what price has to do with doing the job right. This installation could have been done a lot neater at no additional cost.

Part of the code does specify neatness. Not sure exactly how it is worded but it might be hard to enforce because as you say beauty is in the eyes of the beholder and there are a lot of safety wise OK ways to do things that may not be esthetically appealing.

I am sure there are many fine electricians out there but this kind of thing happens all to often especially in mass produced housing developments.

I wonder why this house needs this kind of service. Most be a lot of square footage.
 
  #13  
Old 08-02-08, 09:39 AM
H
Member
Thread Starter
Join Date: Jan 2004
Location: United States
Posts: 1,197
Received 0 Votes on 0 Posts
I got what I paid for? I didn't bid this out and pick the electrician. I am putting on a major addition and my service had to be moved. So my general contractor was responsible for having it done. The general contractor was not cheap. I do not think the inspector saw the work after it was done. (I think I mentioned that somewhere) He was there after the SER cable was run from outside to the circuit breaker boxes. then the electric company contractor came and did the work along with the hired electrician. I never saw inspector again. He may have been there, but I didn't see him. As far as why I need that much power--the house already had it because it used to be separated into an upstairs and downstairs. people lived on first floor and their kid (who I guess was not very responsible) lived on second floor and he had his own bill. the house had two separate HVAV systems, two water heaters, two stoves. Now my addition is 3 floors of 23x30 (master suite on top, family room and office on 1st floor and finished basement with perhaps a kitchenette) a 10x15 dining room. a 24x28 garage. in addition to the 1440 sqft of original house. I have two separate heating/cooling systems, I have a large pool which has two 230v pumps that run 10hours/day. My garage is going to have my air compressor and other power tools and I have a large outbuilding that is going to become a workshop and it also has two other rooms used mainly for storage at this point. so that is why I need 400amps!

as for the workmanship, should I call inspector and see if he will come and take a look? putting in a cable strap is something I could do myself-no big deal as I alread noticed that it didn't seem right but didn't know the code at the the main disconnect as to where it is to be secured. so the grounding rod should have separate wires going to each disconnect? seems pretty easy fix. note that there is only one wire that follows the SER to box area and attaches to water main. Should there be two of these also-one for each disconnect? that would be a pain to do. as for a second grounding rod-also doesn't seem like big deal-$15 and an hour of my time. would I have to have two continuous wires (one for each disconnect) that run from each rod rod to the two disconnects? or can you acorn a piece of wire from one rod to the next?

this electrician did not do anything else in my house. nothing behind drywall. only one person mentioned problem with the ground bus in box. how should that be dealt with?

thanks
 
  #14  
Old 08-02-08, 12:09 PM
F
Member
Join Date: Mar 2006
Location: NE Wis / Paris France{ In France for now }
Posts: 4,807
Received 0 Votes on 0 Posts
I will have to refrain my bad french cussing here.,,

However.,, with the grounding wires with that photo hard to see if that is #8 or #6 if that the case if the #8 or #6 go to ground rod if #8 it will not meet the code at all #6 may be ok if this was a 200 amp service but however with class 320 service { resdential 400 amp service } you need upsized the EGC conductor to #4 and for bonding if you have city water system that will need to be #2 bare copper per NEC codes

For the workmanship that is no excuse espcally with service riser techally wise yeah it meet the code but with the riser you must have equal leght on parallel conductors and IMO it is uneven the shorter cable will draw more current htan longer cable.

It will look more nicer in pipe { in PVC or EMT or Rigid conduit }

For myself for the riser I use the 500 MCM { KCM } for class 320 system { the cost is about the same as pair of 4/0's SE }

I can understand when you mention the setup that make sense when you say everything is " double " but really is your house is 1440 or 2300 sqft ??

Now I know someone mention my name related to this mess but however with the ground bussbar that is very poor set up with single screw in the box on side of it,

Normally with that set up I will use two screws and make sure you scrape the paint off where the nuts or screw will land otherwise it will act like insluating prevent getting good conductive there.

Yes the code do allow that set up but hard to see the photo if you have nuts on both side of the panel { we call them tub } and paint is scrapped off then you are ok on that.

The code do not allowed simple sheet metal to screw in the box it have to be bolted or self tapping machine screw or machine screw or other as i mention above.

If you have more question just holler here we will try to help you much as we can.

Merci,Marc
 
  #15  
Old 08-02-08, 11:26 PM
H
Member
Thread Starter
Join Date: Jan 2004
Location: United States
Posts: 1,197
Received 0 Votes on 0 Posts
thanks french

I took some photos of my disconnect as I said I would





so the neutral and ground are bonded in disconnect making my main panels actually subpanels.

I measured the grounding wires. from rod to disconnect it was about 4.1mm (I think #6?) and from disconnect to water main it was 5.1mm (#4?). so the #4 should be #2? The inspector definitely saw that as he was here when they had the SER cables and ground system roughed in. From what I read, I could get away with one ground rod, with the plumbing being counted as the second, if 1. ground attached to plumbing within 5ft of entrance into house 2. water main buried for at least 10ft. I still may add at least one more grounding rod and from what I can gather, the wire should be continuous from rods to disconnect meaning I would have to replace the wire that is already there. Should I call inspector to have him look it over and if not up to code then call the electrician or the general contractor who hired him?

yes, there are actually three nuts on the bolts holding ground bus. one that you can see in photo right on side of bus, one on inside of box and one on outside of box.

as far as size of house, It will be 3660 sqft (thats counting my new basement with bathroom and kitchenette which doesn't count sometimes as far as real estate agents go) + an old unfinished basement with freezer and fridge/freezer and dehumidifier + 24x28 garage which will have power tools, air compressor + a large 3 room outbuilding with tools (table saw, miter saw, shop vac), dehumidifier and occasionally room AC + pool. Thats if it ever gets finished! I definitely need the 400 amp service. not only for amperage but also for space. I already have one box full and about 1/3 of other. I am in process of trying to tidy up the circuits. some way overload, some with single outlet, code violations (bathroom shares circuit with other rooms, boxes recessed in wall) some metal boxes with bx that has no ground and using armour as ground and has insulation that is brittle. once I get things squared away, i should have some room left over. since I should room., is it ok to wire circuits room by room-foyer, bedroom1, bedroom2, bedroom3, living room, office, etc. instead of having circuits spread out running lights and outlets in multiple rooms.

thanks
bill
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: