250.32

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moyeraa

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250.32 (A) says that a structure supplied by either a feeder or branch circuit shall have a grounding electrode or grounding electrode system installed. However, 250.32 (A) exception states that a structure supplied by a single branch circuit doesn't need a grounding electrode. Even if a structure is only supplied by a single branch circuit, this single branch circuit could still supply a huge amount of power to a structure. Why would this structure disconnect not require a grounding electrode?
 
I can only assume that the thinking is that the equipment grounding conductor will handle the situation. In past codes the equipment grounding conductor was not allowed to double as a grounding electrode conductor but with the 2014 it appears that in many cases the equipment grounding conductor can be used as a grounding electrode conductor. Not sure this answers ours question.... best I could come up with
 
moyeraa said:
250.32 (A) says that a structure supplied by either a feeder or branch circuit shall have a grounding electrode or grounding electrode system installed. However, 250.32 (A) exception states that a structure supplied by a single branch circuit doesn't need a grounding electrode. Even if a structure is only supplied by a single branch circuit, this single branch circuit could still supply a huge amount of power to a structure. Why would this structure disconnect not require a grounding electrode?
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What do you mean "huge amount of power"?
 
The ground electrode will not make a significant difference in the fault current impedance, do I would be more inclined to question why the building ground is required in the first place given a properly sized EGC.
I guess that lightning induced currents would be bypassed around a high EGC impedance at high frequencies. Which brings us right back to why it would not be needed if only a branch was run to the building. :)
 
Dennis Alwon said:
... In past codes the equipment grounding conductor was not allowed to double as a grounding electrode conductor but with the 2014 it appears that in many cases the equipment grounding conductor can be used as a grounding electrode conductor. ...
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In my opinion the only code that has ever prohibited using a single conductor as both the EGC and the GEC was the 2011 code. The 2014 exception to 250.121 puts us back exactly where we were before 250.121 was added to the code in 2011.
 
as for a huge amount of power - suppose one had a 200HP motor as the only load under a 3 sided shed.

it is a structure, but it only has one branch circuit so no GE is required.
 
petersonra said:
as for a huge amount of power - suppose one had a 200HP motor as the only load under a 3 sided shed.

it is a structure, but it only has one branch circuit so no GE is required.
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I know, I just wanted clarification. Not that a GE would make a difference if it was 200 amps or 20 amps.
 
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