Seperately Derived System - Inspector issue.

[kwired]

Consider this.

The NEC has a requirement for disconnecting means when we bring power to a structure. 225.31


225.32 goes on to tell us the required location for that disconecting means. There are four exceptions to that section. I think exceptions three and four are worth a looking at.




That tells me that the NEC considers things as simple as a pole holding a light 'a structure'. If not there would be no need of those exceptions.


Now perhaps a pile of electrical equipment sitting on the ground is not a structure but as soon as you put a support into the ground and hang the electrical equipment from it you have built or constructed a structure.

In my opinion Mr Sargent was shooting from the hip or maybe his answer was misunderstood.

I agree. Take a simple meter pedestal with service disconnect in it.
Is it a structure? If not what is it?
Does it require its own grounding electrode system?
Isn't whatever it is supplying also a separate structure unless it is attached to said pedestal?

 

[mwm1752]

The question posed was very descriptive at the time. I do respect your opinion though -- IMO I've always thought the definition of structure was vague.

 

[kwired]

The question posed was very descriptive at the time. I do respect your opinion though -- IMO I've always thought the definition of structure was vague.

It is vague, to the point that it includes almost anything imaginable. Anything naturally occuring is just about the only things that are excluded.

 

[FREEBALL]

ok from my experience if the neutral is bonded to the ground on the genset, then it is a sep derived system and if you do not remove the bond then the neutral needs to be disconnected along with the ungrounded conductors at the main. Now if you do remove the bond then it is a NSD system. The reasoning I found was that if the neutral and ground are bonded at genset and the main then there is a risk of shock from stray current flowing back on the ground, which would include the frame of the generator. Now if you are using the generator because of a storm or other weather event this could impose a shock hazard. Now as far as the GEC at the generator generac also informed me regardless if the system is NSD or not they require this for lightning strike. Ok so this is a "per manuf. spec." issue and you have to deal with it. But the 17.5KW I installed was not bonded, but I still had to ground as the manuf. specs. to be in accordance with NEC.