Mcc room

[dburney]

I have a mcc room that was built to conveyors in a pellet facility. The room was built outside the main building because of dust. The mcc is 480 and also has a transformer in it. My question is should the conduits have seal offs before entering the building since it is an explosive environment and should the be any type of fire protection in the room forgot to mention the frame of the room is exposed wood withtin on the outside thanks

 

[petersonra]

I have a mcc room that was built to conveyors in a pellet facility. The room was built outside the main building because of dust. The mcc is 480 and also has a transformer in it. My question is should the conduits have seal offs before entering the building since it is an explosive environment and should the be any type of fire protection in the room forgot to mention the frame of the room is exposed wood withtin on the outside thanks

just because there is some dust does not mean the area is classified.

I am not real familiar with class II areas but I don't recall that there is any requirement for seals at all when transitioning from a division 2 area into an unclassified area. personally, I might use some duct seal to reduce any chance of dust getting into my MCC, but I don't think it is required.

This is probably best answered by an actual expert Bob Alexander who generally responds to such questions in the classifed areas forum.

 

[Jraef]

The sawmill / pellet mill itself would be Class III, Div 1 if it's the manufacturing area, Div. 2 if it's a storage area. Most of the time, the MCC is put in another building so it is neither. There is no requirement for seals in conduits entering or exiting the area, but any j-boxes in the areas need to be dust tight: no NEMA 1 in other words. That doesn't mean it's not a good idea, so nothing is stopping you from sealing them. Read article 503 in detail, there are lots of issues to consider, but no sealing. Sealing is a Class I issue for the most part, or when something goes into or out of a Class I to a Class II or III area.

I spent 12 years in the Pacific North West working in numerous lumber, paper and pellet mills, sawdust is permanently embedded in my lung tissue. On one project where we put in a new MCC at an old mill, I had a similar concern strictly from a contamination standpoint, so I packed the conduits with duct seal compound just on general principals. The plant electrician saw me do that and said "What's that stuff?" Does that tell you something?