Ground rod necessary?

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ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
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Consulting Electrical Engineer - Photovoltaic Systems
When supplying a free standing building with a feeder from another building, does there need to be a ground rod at the building being fed? My gut says yes but I am having trouble finding the pertinent code reference.
 
There needs to be a GES which can be ground rod(s) or some other electrode. You'll need two rods or prove that a single rod is 25Ω or less if you are using rod electrodes..
 
Per 250.32(A) Exception you can avoid having to install a grounding electrode and conductor (GEC) if you feed the building with only a single (or single multi-wire ) branch circuit that has an equipment grounding conductor run with it. I am currently laying out just such a system.....but I'm going to put a grounding electrode and conductor in anyway so that I can add another circuit or other conductors (such as switch legs, control wires, etc.) later on between the buildings.
 
If you have multiple circuits how do you get around 225.30?

Part II. Buildings or Other Structures Supplied by a Feeder(s) or Branch Circuit(s)

225.30 Number of Supplies. A building or other structure that is served by a branch circuit or feeder on the load side of a service disconnecting means shall be supplied by only one feeder or branch circuit unless permitted in 225.30(A) through (E). For the purpose of this section, a multiwire branch circuit shall be considered a single circuit. Where a branch circuit or feeder originates in these additional buildings or other structures, only one feeder or branch circuit shall be permitted to supply power back to the original building or structure, unless permitted in 225.30(A) through (E).
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infinity said:
If you have multiple circuits how do you get around 225.30?
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He didn't say there were multiple circuits. But he did use the word "feeder." That leads me to believe that the separate building will have a panel of its own. If so, then a local GES is required.
 
RD35 said:
Per 250.32(A) Exception you can avoid having to install a grounding electrode and conductor (GEC) if you feed the building with only a single (or single multi-wire ) branch circuit that has an equipment grounding conductor run with it. I am currently laying out just such a system.....but I'm going to put a grounding electrode and conductor in anyway so that I can add another circuit or other conductors (such as switch legs, control wires, etc.) later on between the buildings.
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Perfect; that's what I was looking for. It seems to me that in my case the exception does not apply since I will be running feeders (not branch circuits) to panels in these two buildings. Am I interpreting this correctly?

Edit: I wrote the above before I read charlie b's response. That's what he said as well, isn't it?
 
ggunn said:
Perfect; that's what I was looking for. It seems to me that in my case the exception does not apply since I will be running feeders (not branch circuits) to panels in these two buildings. Am I interpreting this correctly?

Edit: I wrote the above before I read charlie b's response. That's what he said as well, isn't it?
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Yes that is what he said. Charlie was just stating that you did not have a multiwire branch circuit or a single branch circuit but rather a feeder so you need rods
 
charlie b said:
He didn't say there were multiple circuits. But he did use the word "feeder." That leads me to believe that the separate building will have a panel of its own. If so, then a local GES is required.
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I was responding to post #4.
 
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