Sub-panel feeders

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Difference is quite big. Yes, a fire switch is a main disconnect outside. 680.25 states you need to feed the pool panelboard from an applicable service equipment. Per definitions (my inspector is stating) the service equipment is your main disconnect. So, if you interpret 680.25 "literally"...you must feed your pool panelboard from your main disconnect outside. I do not believe this to be true.

Question? Your meter socket/disconnect combo is grounded with an non-insulated ground. Your main lug only 225A panel inside is fed with an non-insulated ground. You 125A sub-panel is fed with an non-insulated ground. So why does it matter where the "insulated-ground" feeding the pool panelboard comes from. EVERYTHING power source has an non-insulated ground.

My state DCA is actually contacting NFPA to come up with an answer and/or explanation................

Thoughts?
 
The first question to ask is why do they even require an insulated ground. Without knowing that, you can't answer why they care where the insulation starts. Code says insulated from the Service, but doesn't say why. If an upstream subpanel was wired with a raceway, then pulling a new insulated EGC to the parent panel isn't hard. But if it used NM or SER cable, that could get rather expensive and seems to be of dubious value.

One could also ask the efficacy of this insulated ground if you choose to run that feeder in rigid metal conduit or EMT (pool feeders must be in a raceway). That metal conduit takes the same path and would be exposed to whatever a bare EGC would be exposed to. There is no requirement to isolate the pool panel from any metal raceways.
 
One guess: an insulated EGC is less likely to corrode away unseen in the corrosive atmosphere of pool water and chemicals.
Any damage would be limited to visible damage at the ends. Also no chance of galvanic corrosion in contact with raceways or fittings.
There may be some clues to the CMP's motivation in the record from when the provision was adopted.
 
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