I need to install conduit and receptacles in a large cold room that the fire marshall has classified as Class1 division 2 location. (they store flammable chemicals in this room) The walls of the cold room are lined with 3" foam, my two questions are:
1. how do mount conduit and or boxes to a foamed wall. Do i need to penetrate through the foam and mount to concrete or there are special hardware for foam?
2. I am not very familiar with article 500, is EMT allowed with this location?
Class1 Div 2 requires threaded IMC or RMC, no EMT.
You could put lag shields into the concrete and use conduit hangers on 4 1/2" or 5" hanger bolts ("wood screw thread on one end, machine thread on the other)with a jam nut on the machine thread at the surface of the foam and another nut securing the hanger.
it is not seamless, it just doesn't have any rigid piece to it. It is not like the regular walk in freezers and similar have sheet metal walls with foam inside but this one is only foam with foil covering.
I saw a flower cooler like that when my wife was in the flower biz. The sheet metal box is mostly for the health inspector from what I see. They need to be able to wash it down. I did not pay attention to how they hung the lights and they were not dealing with Art 500. This was Miami before Andrew. It may have been festoon lamp bases on an orange cord in those days. ;(
I can't check with the manufacturer because the room is built on site. Imagine a warehouse with concrete walls and it has foam board glued to the concrete walls. It is more less a room with an oversized AC that keeps the room cold and this cold room is built inside a 30 sqft warehouse that stores corrosive material.
I think i will do all of the conduit work on the outside of this cold room then penetrate into the cold room. That will eliminate the RMC conduit + the associated labor, and .....
Now, the question can i seal my penetrations with Fire putty or caulk?