Common question.Im getting conflicting stories,which one is true. seperate building with no connections what so ever to other building,water pipe etc,etc.Main building is where service is.I will bring a feeder to seperate building for a number of branch circuits.I already know about a single circuit with an equipment ground does not require a ground rod.What im being told is if i do not run a ground i have to drive a groundrod,no problem. but im also being told if i do run an equipment ground with my hots and neutral i do not need a ground rod.please help..the other question is if i do not run a ground and drive a rod does the neutral stay isolated or is this application considerd a service where i would bond the neutral to the groundrod and panel..I know this may be simple but i have to sources with different views. Thank you
seperate building
- Thread starter bond
- Start date
- Status
- Location
- Massachusetts
Re: seperate building
All separate buildings or structures with feeders or more than one branch circuit require grounding electrodes. 250.32(A)
You have the option of running a EGC or not running an EGC.
Run an EGC and follow the rules in 250.32(B)(1)
OR
Do not run an EGC if you can meet the requirements of 250.32(B)(2).
Most times you are better off running the EGC in my opinion.
All separate buildings or structures with feeders or more than one branch circuit require grounding electrodes. 250.32(A)
You have the option of running a EGC or not running an EGC.
Run an EGC and follow the rules in 250.32(B)(1)
OR
Do not run an EGC if you can meet the requirements of 250.32(B)(2).
Most times you are better off running the EGC in my opinion.
crossman
Senior Member
- Location
- Southeast Texas
Re: seperate building
1) No matter what, the grounding electrode will have to be established at the second building.
This grounding electrode shall be installed according to 250.50 and this may mean more than just a ground rod (may not even need a ground rod). May be the water pipe and the building steel and the concrete encased electrode and whatever else is available... is present...?
2) The feeder will most likely need an equipment ground. The neutral (grounded conductor) and neutral (grounded conductor) bar at the second building would need to be kept separate from the equipment grounds. All branch circuit neutrals (grounded conductors) would need to be seperate from the equipment grounds. (a feeder to a subpanel)
3) If there are no metallic paths between the two structures and if there is no GFPE ahead of the feeder, then the neutral (grounded conductor) can be used to bond the equipment grounds in the second building. The neutral (grounded conductor) bar would be attached to the equipment grounds. (similar to a new service)
Section 250.32
1) No matter what, the grounding electrode will have to be established at the second building.
This grounding electrode shall be installed according to 250.50 and this may mean more than just a ground rod (may not even need a ground rod). May be the water pipe and the building steel and the concrete encased electrode and whatever else is available... is present...?
2) The feeder will most likely need an equipment ground. The neutral (grounded conductor) and neutral (grounded conductor) bar at the second building would need to be kept separate from the equipment grounds. All branch circuit neutrals (grounded conductors) would need to be seperate from the equipment grounds. (a feeder to a subpanel)
3) If there are no metallic paths between the two structures and if there is no GFPE ahead of the feeder, then the neutral (grounded conductor) can be used to bond the equipment grounds in the second building. The neutral (grounded conductor) bar would be attached to the equipment grounds. (similar to a new service)
Section 250.32
- Location
- Windsor, CO NEC: 2023
- Occupation
- Hospital Master Electrician
Re: seperate building
I agree, Bob. Problem is, it's more expensive (another conductor), and the slightest bit more involved. Can you tell me conditions that would push you over the edge and run an EGC, so that I can use that argument in the future?
Re: seperate building
George, I will give you my two cents worth. I always specify an EGC unless it is new construction, and I am 110% sure there is no other metallic paths. By running the EGC you are safe whether or not another metallic path exist or not.
[ January 04, 2005, 10:34 PM: Message edited by: dereckbc ]
George, I will give you my two cents worth. I always specify an EGC unless it is new construction, and I am 110% sure there is no other metallic paths. By running the EGC you are safe whether or not another metallic path exist or not.
[ January 04, 2005, 10:34 PM: Message edited by: dereckbc ]
pierre
Senior Member
- Location
- Westchester County, New York
Re: seperate building
To add to Derek's post, if you do run an equipment ground conductor, you also ensure that any future installation from one building to the other that may include a metallic path will not create a problem.
Pierre
To add to Derek's post, if you do run an equipment ground conductor, you also ensure that any future installation from one building to the other that may include a metallic path will not create a problem.
Pierre
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: seperate building
Keep in mind a phone or tv cable can also cause this path if they are grounded at both ends. The tv cable can shere in the neutral current which it is not sized to do and can cause a fire.
Just something to think about.
A phone conductor would be unlikely to be grounded but you never know.
Keep in mind a phone or tv cable can also cause this path if they are grounded at both ends. The tv cable can shere in the neutral current which it is not sized to do and can cause a fire.
Just something to think about.
A phone conductor would be unlikely to be grounded but you never know.
- Location
- Massachusetts
Re: seperate building
Personally the only time I can see not running an EGC would be out to a very remote building like a pump house that will never have phone or cable service and is not connected to the main building with metal water line.
However I have never done that.
I usually work with engineered prints and I have never seen any engineered prints that did not call for a EGC run to a separate building, as a matter of fact we get some prints that show an EGC with the service conductors which is a mistake.
Personally the only time I can see not running an EGC would be out to a very remote building like a pump house that will never have phone or cable service and is not connected to the main building with metal water line.
However I have never done that.
- Location
- Illinois
- Occupation
- retired electrician
Re: seperate building
I still fail to understand why three wires to a second building can be a hazard and three wires from a service is not a hazard. The same conditions exist. Metal water pipes, TV cable shields, underground phone line shields and I'm sure other parallel paths exist on the service side. Why are parallel paths ok on the service side and not on a feeder to a second building? How do the electrons know who owns them?
NOTE: I'm not saying that you don't have to comply with the code, I am just wondering about the reasons behind rules that are different, but the electrical circuits are the same.
Don
I still fail to understand why three wires to a second building can be a hazard and three wires from a service is not a hazard. The same conditions exist. Metal water pipes, TV cable shields, underground phone line shields and I'm sure other parallel paths exist on the service side. Why are parallel paths ok on the service side and not on a feeder to a second building? How do the electrons know who owns them?
NOTE: I'm not saying that you don't have to comply with the code, I am just wondering about the reasons behind rules that are different, but the electrical circuits are the same.
Don
jtester
Senior Member
- Location
- Las Cruces N.M.
Re: seperate building
Don
I agree with your post, I brought up the same thought in another thread. As a utility employee, for years I ran 3 wire services to buildings without regard to the fact that they had other metallic paths joining them. Utilities still do. Neutrals are significantly lower impedances than CATV or phone grounds, so they may not be adversely affected, but metal water pipes are low impedance as well. What gives?
Jim T
Don
I agree with your post, I brought up the same thought in another thread. As a utility employee, for years I ran 3 wire services to buildings without regard to the fact that they had other metallic paths joining them. Utilities still do. Neutrals are significantly lower impedances than CATV or phone grounds, so they may not be adversely affected, but metal water pipes are low impedance as well. What gives?
Jim T
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- Semi-retired engineer
Re: seperate building
perhaps the theory is that it is unlikely someone will come in close contact with the service run from the utility pole.
perhaps the theory is that it is unlikely someone will come in close contact with the service run from the utility pole.
crossman
Senior Member
- Location
- Southeast Texas
Re: seperate building
There is much to discuss on this subject and I hope it continues. I will ask questions and put in my two cents worth eventually and hopefully I will learn something.
There is much to discuss on this subject and I hope it continues. I will ask questions and put in my two cents worth eventually and hopefully I will learn something.
O
oliver100
Guest
Re: seperate building
I wonder if a feeder to a separate building with 2 or more branch circuits could be 2 wire (black, white, EGC) 120 volts.
I wonder if a feeder to a separate building with 2 or more branch circuits could be 2 wire (black, white, EGC) 120 volts.
jimwalker
Senior Member
- Location
- TAMPA FLORIDA
Re: seperate building
Why not? I see no reason to have both phases other than wire size would be smaller if you share a neutral
Why not? I see no reason to have both phases other than wire size would be smaller if you share a neutral
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: seperate building
Sure.
- Status