Two generators, one MTS... Do the same switching rules apply?

FAZERS

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Location
Dallas
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Engineer
A while back, I posted a thread about the configuration of a MTS between two neutral-ground bonded 208Y gensets regarding some details about their grounding conductors. I briefly mentioned with the generator being configured how it was, that it would probably be considered a SDS for this application and that I assumed the MTS would be a switched 4Pole. It's been a minute, but I believe we ended up receiving a 4P MTS from our electrician however with the neutral being non-switched.. and it appears it was installed as such.

It's a trailered, off-grid oilfield application that has a backup generator system for high-availability service. The generators don't ever run at the same time. The application is a bit unusual, if only for the fact it's for two SDS gensets and is never grid-tied or grounded to any external equipment/electrodes on location outside of the grounding rod included with the drop-deck trailer it's on. Both gensets are bonded/bolted to the (metal) frame.

Does the off-grid use, common electrode (frame) or guaranteed mutual exclusion of the gensets running change anything within NEC classification, or will we need to get this resolved pretty quickly?

Attached is a photo of the MTS, neutral unswitched. It looks like we extended the ground conductors to join together at the MTS box despite the neutral-ground bond at the genset terminals.

Thanks,
 

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