For several years and in several jurisdictions we have been installing residential hot tubs on decks as follows (all have passed inspections): 6-3 RX thru the house to a panel mounted on the exterior wall (as per 680-25c Ex3). From that point it's piped with the insulated ground. Last week one of the jurisdictions (where we had never installed one) said that under 680-25d the tub contained a panel board and needed the insulated ground all the way back to the main service (i.e. pipe the whole thing). We maintained that the tub is a factory sealed and approved unit and 680-25c Ex3 could be applied. Well it wasn't worth the fight so we did it his way but the customer paid a premium. What's your opinion?
Since it's a listed factory unit, a call to the manufacturer might have been able to shed some light. If you use there units regularly, give it a try.
"Famous Names" BTW, One of the owners of the company I work for, although no relation to the other, is named...Mike Holt. On one job I worked on, the GC's super was named Neil Young, and the owner's rep was named Jim Nabors..for real
I brought this up a few times(see previous topics). I use ENT with insulated ground instead of NM. Heres why-- 680-12 requires disconnect. 680-25(d) requires panelboards and DISCONNECTS to have an insulated ground. 680-25(c) requires motors have an insulated ground, with permission for interior of single family dwellings to use NM (a chapter 3 wiring method). 680-25(d) does not include the permission for single family dwellings. Therefore, NM not allowed.
I have seen many NM installations. Apparently it's often accepted.