A farmer asked me to wire up a new building on his property. There is an existing building aproximately 15 ft. away with a 100A panel panel with two 20A circuits being utilized for a light and outlets. I'm going to install a 60A two pole breaker in this panel and pull over three No.6's. to the new building and feed a 60A panel. My question is, Do I establish a new ground(install a ground rod in the new building) or continue the ground from the existing building.
proper grounding
- Thread starter jhg
- Start date
- Status
- Location
- Illinois
- Occupation
- retired electrician
You need to install an EGC with the feeder and you need to install a grounding electrode at the second building and bond the grounding electrode to the EGC, not the grounded conductor, at the second building.
mcclary's electrical
Senior Member
- Location
- VA
Welcome to the forum. I'd also like to add that Don's answer is based on the 08' code. In VA, we're still on 05', so the 3 wire setup would be perfectly legal barring any other metallic paths
dcspector
Senior Member
- Location
- Burke, Virginia
And don't forget about 200.6(A) if not using a cable assembly.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
JH, welcome to the forum! 
In a nutshell, the new panel should be wired with a 4-wire feeder, like a sub-panel, with separated neutral and grounding, and should also be installed as if it were a service, with a main disco (or 6-handle limit) and complete grounding-electrode system. The main difference is that you do not bond the neutral anywhere in this building.
Mr. McC is correct that the '05 still alows the 3-wire feeder, which you would wire exactly like a service, including bonding the neutral, and the electrode system, but most guys here would recommend the 4-wire approach, even if the 3-wire was permitted. I'm flexible on the issue, but a 15' feeder isn't very expensive to add a fourth wire to.
Added: Note that, if the existing 100a panel is itself supplied via a 4-wire feeder, you have no option: you must maintain the unbonded neutral system throughout the entire new installation.
In a nutshell, the new panel should be wired with a 4-wire feeder, like a sub-panel, with separated neutral and grounding, and should also be installed as if it were a service, with a main disco (or 6-handle limit) and complete grounding-electrode system. The main difference is that you do not bond the neutral anywhere in this building.
Mr. McC is correct that the '05 still alows the 3-wire feeder, which you would wire exactly like a service, including bonding the neutral, and the electrode system, but most guys here would recommend the 4-wire approach, even if the 3-wire was permitted. I'm flexible on the issue, but a 15' feeder isn't very expensive to add a fourth wire to.
Added: Note that, if the existing 100a panel is itself supplied via a 4-wire feeder, you have no option: you must maintain the unbonded neutral system throughout the entire new installation.
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If there is livestock involved run the EGC and bond it to the new ground rod or UFFER, if you have one. There are so many times people are wondering "why are the horses are getting shocked when they ..........." the problem is always bad grounding issues. Keep the grounded(neutral conductor) separated from the EGC, except at the service, and you will have far fewer issues down the road. IMO
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