I have a job which requires installation of a 60 amp 120/208 1ph service panel in an unattached pole building at a local school. The architect's drawing shows feeding this panel from a 3ph 4-wire sub panel in the main building. Is this OK,ie; feeding a sub from a sub? If so how do I properly address the issue of bonding and grounding? Thanks in advance for your help.
service panel in an unattached building
- Thread starter bmc
- Start date
- Status
russ
Senior Member
- Location
- Burbank IL
Re: service panel in an unattached building
Yes it's ok, just install the feed with the proper wire and over current protection.
Install an equipment ground with the circuit and do not bond the grounded conductor to the ground at the pole building. Do install a ground rod at the pole building and bond that to the equipment gound not the grounded conductor.
Read 250.32
Yes it's ok, just install the feed with the proper wire and over current protection.
Install an equipment ground with the circuit and do not bond the grounded conductor to the ground at the pole building. Do install a ground rod at the pole building and bond that to the equipment gound not the grounded conductor.
Read 250.32
- Location
- Massachusetts
Re: service panel in an unattached building
You will need a grounding electrode at the detached building.
You will need a grounding electrode at the detached building.
Re: service panel in an unattached building
Just to make sure I got this straight-
Run my two hot conductors and neutral,(or grounded coductor), from the sub panel and install a ground electrode at the pole building. Attach to the disconnect and panel, but do not bond.
In essence, since there is no ground electrode at the feeding sub, only a grounded conductor, I would supply the ground electrode at the new service.
Just to make sure I got this straight-
Run my two hot conductors and neutral,(or grounded coductor), from the sub panel and install a ground electrode at the pole building. Attach to the disconnect and panel, but do not bond.
In essence, since there is no ground electrode at the feeding sub, only a grounded conductor, I would supply the ground electrode at the new service.
- Location
- Windsor, CO NEC: 2017
- Occupation
- Hospital Master Electrician
Re: service panel in an unattached building
4 wires: 2 ungrounded, 1 grounded, 1 grounding, plus one ground rod.
An alternate method is detailed in 250.32 (B)(2). There are fewer hoops to jump if installed per 250.32(B)(1), the method Russ, Bob and I have outlined above.
Edit:
Surely there must be grounding conductors at the feeding subpanel? Your grounding conductor for the detached building would be terminated in the grounding bar in that subpanel.
[ December 12, 2004, 01:19 PM: Message edited by: georgestolz ]
4 wires: 2 ungrounded, 1 grounded, 1 grounding, plus one ground rod.
An alternate method is detailed in 250.32 (B)(2). There are fewer hoops to jump if installed per 250.32(B)(1), the method Russ, Bob and I have outlined above.
Edit:
Surely there must be grounding conductors at the feeding subpanel? Your grounding conductor for the detached building would be terminated in the grounding bar in that subpanel.
[ December 12, 2004, 01:19 PM: Message edited by: georgestolz ]
Re: service panel in an unattached building
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Tom H
The confusion could well be caused by the system at the school using raceways and cable armor as the Equipment Grounding Conductor (EGC). There may well be no EGC in the form of a wire or buss bar in the panel that the feeder will be run from. If that is true then the place to terminate the GEC that will be run in the feeder to the pole building would be a bonding bushing installed on the feeder raceway or cable connector threads of the feeder that supplies the source panel. Alternatively you could just mount a lug in and bonded to the cabinet that encloses the source panel.
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Tom H
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