I'm alittle confused about separating the neu. and ground at a subpanel. I have a meter with a 200 amp service disconnect, two hot lines a neutral and ground conductors together on same bar going to an electrode. This feeds a subpanel thru PVC to the house with the two hot lines and the neutral only, no ground conductor. I'm looking at Mike's 2002 guide and it says to separate the neutral and ground at the subpanel. On page 168 Figure 250-90 it shows to add a jumper between the neu. and grd. The figure shows my situation. I guess my question is if you run a ground conductor with the feeders to the sub it should be separated. If there's no ground you combined the neutral with the ground to an electrode?
Separating Neutral and Ground at subpanel
- Thread starter mikebrink
- Start date
- Status
- Location
- Illinois
- Occupation
- retired electrician
Re: Separating Neutral and Ground at subpanel
Mike,
In general you are required to run the grounding conductor to any panel that is on the load side of the service disconnect.
Don
Mike,
In general you are required to run the grounding conductor to any panel that is on the load side of the service disconnect.
Don
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: Separating Neutral and Ground at subpanel
I don't have a copy of that book, so I am not certain how closely the situation you describe matches the figure you cited. Part of my uncertainty relates to your use of the term "subpanel." You mention a meter, then you mention a panel. Is this the "main service panel"?
As Don said, you connect neutral to ground at the first disconnecting means, and not again thereafter. That is why you may read that you do not connect N-G at a "subpanel." That phrase is generally understood to mean a panel downstream of the main service panel.
You need to understand that there are two separate phrases that each use the word "grounding." One is the "Grounding Electrode Conductor." That goes from the point at which the N-G bond takes place, and goes to the ground rod. The other is the "Equipment Grounding Conductor." That goes from the external metal parts of any equipment, and goes back to the Ground Bar in the panel that feeds the equipment.
So help me understand your situation. Is the service disconnecting means outside the house, at the meter, with the N-G bond taking place outside the house, and the GEC running from that point to the ground rod? If so, then from that point into the house there needs to be two hot conductors, one neutral, and one EGC. Once these reach the panel inside the house, connections to the neutral bus must be kept separate from connections to the ground bus.
Does this answer your question?
I don't have a copy of that book, so I am not certain how closely the situation you describe matches the figure you cited. Part of my uncertainty relates to your use of the term "subpanel." You mention a meter, then you mention a panel. Is this the "main service panel"?
As Don said, you connect neutral to ground at the first disconnecting means, and not again thereafter. That is why you may read that you do not connect N-G at a "subpanel." That phrase is generally understood to mean a panel downstream of the main service panel.
You need to understand that there are two separate phrases that each use the word "grounding." One is the "Grounding Electrode Conductor." That goes from the point at which the N-G bond takes place, and goes to the ground rod. The other is the "Equipment Grounding Conductor." That goes from the external metal parts of any equipment, and goes back to the Ground Bar in the panel that feeds the equipment.
So help me understand your situation. Is the service disconnecting means outside the house, at the meter, with the N-G bond taking place outside the house, and the GEC running from that point to the ground rod? If so, then from that point into the house there needs to be two hot conductors, one neutral, and one EGC. Once these reach the panel inside the house, connections to the neutral bus must be kept separate from connections to the ground bus.
Does this answer your question?
Re: Separating Neutral and Ground at subpanel
Bond at the main panel. seperate at the sub panel.
I dont know of any situation where, if you are staying in the same building, it is ok to not have a seperate ground at a sub panel. If there is not one there you need to run one.
Bond at the main panel. seperate at the sub panel.
Re: Separating Neutral and Ground at subpanel
Let me try to explain this using the correct wording. I'm looking at a detached garage with a "main service disconnect", which includes the "Grounding Electrode Conductor". This feeds the house disconnect thru PVC with two hot leads and one neutral, NO "Equipment Grounding Conductor". The house disconnect has it's own grounding electrode (ground rod). Should the N-G still need to be separated at the house disconnect? I can't verify that there is any metal water or gas pipe (which is bonded at the house disconnect) going to the detached garage where the main service is located.
Let me try to explain this using the correct wording. I'm looking at a detached garage with a "main service disconnect", which includes the "Grounding Electrode Conductor". This feeds the house disconnect thru PVC with two hot leads and one neutral, NO "Equipment Grounding Conductor". The house disconnect has it's own grounding electrode (ground rod). Should the N-G still need to be separated at the house disconnect? I can't verify that there is any metal water or gas pipe (which is bonded at the house disconnect) going to the detached garage where the main service is located.
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: Separating Neutral and Ground at subpanel
That is the key issue at this point. I think you are already aware of this, but the applicable code section is 250.32(B)(2). If that is the article that correctly describes your situation, then there should be an N-G bond inside the house panel.
radiopet
Senior Member
- Location
- Spotsylvania, VA
Re: Separating Neutral and Ground at subpanel
I've got a good one for you.
Q.) You bring the underground service Lat. to a meter cab on a garage it then feeds one panel in the garage ( it's own service) and one main disconnect. The main disconnect is then feeding the seperate building on the property which happens to be the dwelling itself. ( don't ask me why guys...lol..it was e-mailed to me this way )
Now...only (1) Service Latteral and (2) Different services within the large detached garage...one for the gararge which is a house in itself and one for the actual dwelling on the property....both are in the garage and their is a panel in the dwelling with a main as well, the person stated they ran 3-wire and drove (2) ground rods at the dwelling as well as at the garage itself....
now their question is this...is the dwelling treated like a sub-panel per say and would require 4 wires and a ground rod(s) or can you run 3 wires and ground rod(s)at the dwelling....
Personally..here is why I posted this...it was funny as they stated Art 250.32 speaks about COMMON systems...and all that fall under it are considered common....yet these have two different AC system from one meter cab...should the dwelling be treated like a normal dwelling and allow the 250.32(B)(2).....never quite had it presented like that before so I figured you all would have some advice for him...How about it BOB(iwire)...I guess it is the wording " Common Service" in the Art 250.32 that presented this question...
Any thoughts on this...?
P.S. I had to edit this....I forgot to add that the connection between the dwelling and the main disconnect in the garage is tri-plex and not metal conduit..no metal potential for continuous contact exists I am told.
[ December 08, 2005, 11:03 PM: Message edited by: radiopet ]
I've got a good one for you.
Q.) You bring the underground service Lat. to a meter cab on a garage it then feeds one panel in the garage ( it's own service) and one main disconnect. The main disconnect is then feeding the seperate building on the property which happens to be the dwelling itself. ( don't ask me why guys...lol..it was e-mailed to me this way )
Now...only (1) Service Latteral and (2) Different services within the large detached garage...one for the gararge which is a house in itself and one for the actual dwelling on the property....both are in the garage and their is a panel in the dwelling with a main as well, the person stated they ran 3-wire and drove (2) ground rods at the dwelling as well as at the garage itself....
now their question is this...is the dwelling treated like a sub-panel per say and would require 4 wires and a ground rod(s) or can you run 3 wires and ground rod(s)at the dwelling....
Personally..here is why I posted this...it was funny as they stated Art 250.32 speaks about COMMON systems...and all that fall under it are considered common....yet these have two different AC system from one meter cab...should the dwelling be treated like a normal dwelling and allow the 250.32(B)(2).....never quite had it presented like that before so I figured you all would have some advice for him...How about it BOB(iwire)...I guess it is the wording " Common Service" in the Art 250.32 that presented this question...
Any thoughts on this...?
P.S. I had to edit this....I forgot to add that the connection between the dwelling and the main disconnect in the garage is tri-plex and not metal conduit..no metal potential for continuous contact exists I am told.
[ December 08, 2005, 11:03 PM: Message edited by: radiopet ]
radiopet
Senior Member
- Location
- Spotsylvania, VA
Re: Separating Neutral and Ground at subpanel
Well since no one will chime in.....Here is what I ruled on this for the guys.
1.) It was not correct under 250.32(D) since it was considered "remote" from the location and located on the same property.
His argument: The property is a rental and both the garage and the dwelling both has their own permits and since the main panel in the dwelling ALSO has it's own disconnect that it was not under Single Management or quite so remote thus the 3-wire was allowed regardless of the future prospects of objectionable paths....
Anyway.....the local ruling was that it was still considered REMOTE regardless of the main shut off also being in the dwelling and thus has to be ruled under 250.32(D)(1).....
Well since no one will chime in.....Here is what I ruled on this for the guys.
1.) It was not correct under 250.32(D) since it was considered "remote" from the location and located on the same property.
His argument: The property is a rental and both the garage and the dwelling both has their own permits and since the main panel in the dwelling ALSO has it's own disconnect that it was not under Single Management or quite so remote thus the 3-wire was allowed regardless of the future prospects of objectionable paths....
Anyway.....the local ruling was that it was still considered REMOTE regardless of the main shut off also being in the dwelling and thus has to be ruled under 250.32(D)(1).....
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Re: Separating Neutral and Ground at subpanel
Should the N-G still need to be separated at the house disconnect?
The NEC only allows the neutral to be "regrounded" if there are no parallel paths between the two buildings. I don't recommend this practice.
In Washington state this has not been allowed since Aug 2003. regardless of if its under the same management or not, its not a safe practice.
Should the N-G still need to be separated at the house disconnect?
The NEC only allows the neutral to be "regrounded" if there are no parallel paths between the two buildings. I don't recommend this practice.
In Washington state this has not been allowed since Aug 2003. regardless of if its under the same management or not, its not a safe practice.
A/A Fuel GTX
Senior Member
- Location
- WI & AZ
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- Electrician
Re: Separating Neutral and Ground at subpanel
In light of this parallel path discussion, would a cable or phone line qualify as a parallel path?
In light of this parallel path discussion, would a cable or phone line qualify as a parallel path?
jwelectric
Senior Member
- Location
- North Carolina
Re: Separating Neutral and Ground at subpanel
yes if grounded at both places.
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