Inspectors with multiple fault scenarios

[JeffreyP]

I have an inspector failing my site because he thinks he's found a way to get around the safety mechanisms built into my system. He's not technically wrong, but the only scenario he can generate, which isn't purposefully installing the system incorrectly, involves 4 faults, all of which require the active participation of a demonic squirrel who chews all the way through PV wire and is apparently trying to burn my house down.

Regardless of how ridiculous this is, is there anything that specifically spells out in the NEC that ridiculous multiple fault scenarios can be ignored?

So far I can't find anything, but in my time in the Navy as an electronics engineer my training taught me to ignore troubleshooting scenarios generating a fault from a string of unlikely events, and what this inspector is coming up with seems beyond absurd, and changing the system the way he suggests is going to cost me another $2000.

 

[augie47]

Without details, it's hard to judge. Inspectors enforce Code. What Code violations are cited ?

 

[dema]

NEC

NEC

My thoughts exactly. Inspectors don't (or shouldn't) decide what's safe or not. They enforce the NEC regulations. They are enforcing the law, not making it up.

 

[JeffreyP]

Without details, it's hard to judge. Inspectors enforce Code. What Code violations are cited ?

This is in reference to a SolarEdge system. This is an ungrounded PV system with 3 strings. According to SolarEdge, and they have a white paper supporting this, they don't require fusing on 3 strings because their system will protect against it assuming everything is built as it's supposed to be.

http://www.solaredge.com/files/pdfs/string_fusing_requirements.pdf

The inspector is proposing a scenario where there are 3 strings on a system, and on both ends are combined in a combiner box, and (+) and (-) ends are going to the inverter. All conductors are appropriately sized for 15A per string (10AWG on the string side and 8AWG on the inverter side to carry the combined current). He's suggesting that at 6 feet from the (-) end combiner, prior to being combined, that a squirrel chews through 2 of the conductors completely, then chews the insulation from the third conductor and uses his little squirrel hands to push the two ends of the broken conductors to the exposed conductor of the third wire, all without generating a ground fault which would shut the system down. Now, in this scenario, the current from all three strings is going through this 6ft section of wire, exceeding its current limitation, therefore we need fuses on all three strings on both ends, which SolarEdge specifically says are not needed based on their system design.

Yes, he's generated a scenario where the protection is bypassed, but the scenario is so ridiculous I don't think we shouldn't have to shell out $2k to get him to let us turn it on.

 

[jaggedben]

A PV system is supposed to shutdown on the first fault, in any case. So if the resident is paying attention to their usage statement they should notice within a month. And if the roof is Class A, then it should be able to withstand the worst a squirrel can do, too.

What town is this? I might be working there, too.

 

[JeffreyP]

A PV system is supposed to shutdown on the first fault, in any case. So if the resident is paying attention to their usage statement they should notice within a month. And if the roof is Class A, then it should be able to withstand the worst a squirrel can do, too.

What town is this? I might be working there, too.

Westmoreland NY.