Cable Tray Installation

[Nitty]

Commercial Account;
Transformer room houses 2) 1500 KVA Transformers (Primary 8320V). This room is locked and accessible only to qualified personnel. Existing installation uses cable tray and single conductors to supply main disconnects. Customer wants to install a new disconnect off the load side of one of the transformers. According to 392.3(B) this scenario can only be installed in an "Industrial Establishment". None of the existing cable tray leaves the room and the proposed cable tray would not leave the room either. The NEC does not specify what it means by "Industrial Establishment" for this article. The closest I get is 240.2 which describes "Supervised Industrial Installation" but only for application to part 8 of 240. Am I being to nit-picky to say that cable tray should not be used in the new installation?

 

[rbalex]

There is no universal definition of industrial establishment - even using building codes outside the NEC.

Unfortunately, the only significant “line” (and it gets muddied on occasion) is between residential and non-residential which can range from commercial to some institutional to heavy-industrial. However,throughout the NEC, the most common “industrial” qualifiers are limited public access and/or conditions of maintenance and supervision ensure that only qualified persons service the installation. Both appear to apply from the OP.

If you can, find out if the AHJ can make documented distinctions. Personally, I’d have no problem with what you described in the OP.