What is the preferred wiring method for inside walk in coolers and freezers?
I generally see a couple of methods used, that being, some wired entirely with liquid tight flexible metal conduit [LFMC] and others with EMT and rain tight fittings. I've even seen Sch.40 PVC [RNC] used in a walk in cooler before. I guess this is okay since it was mounted on the ceiling close where the joint between the ceiling and wall meet and the cooler temp was normally only around 34-degrees. I would think it would be to brittle for a freezer application, although I’m not sure that it would be a code violation. Sometimes I see a combination of these methods used.
I have also noticed that some mount their conduits right on the walk-in's surface and yet others use minerallac clamps to maintain a 1/4" air space behind them, which I suspect would probably be more in keeping with the Sanitary Code as well as the NEC 300.6[D] spacing for wet locations. Would this spacing only apply when mounting on "wall surfaces", but not ceiling surfaces?
I normally use WP round boxes in walk-in's at splice points or when changing wiring methods and I have noticed there is a slight air space behind these boxes when installed, but it looks to be less than 1/4". Has this air space issue ever been the basis for failing an inspection for a walk-in unit for anyone?
TKX
