science lab fume hood - classification?

[malachi constant]

I have a project where the control wiring for the fume hood exhaust must penetrate the air stream. Control wiring is run in EMT conduit and the question has come up as to whether this should be considered a classified location.

Hood is in a school science lab, chemicals used will be your typical organic industrial solvents, acids, bases etc.

I'm guessing this is Class 1 Div 2, but any thoughts are appreciated. Thanks.

 

[petersonra]

I can't imagine that such an area would be classified at all.

 

[rbalex]

Fume hoods generally fall under NFPA 45, Standard on Fire Protection for Laboratories Using Chemicals. Properly installed, they greatly reduce the Classified Location requirements. (I saved one client $750k on one project showing them how)

As Bob pointed out, it may not be necessary at all; but it does take a knowledgeable evaluation of the total operation.

 

[malachi constant]

The inspector's answer: NEC 300.22 doesn't allow conduit to penetrate the air stream being used for vapor removal. So the conduit will have to be routed elsewhere (which will be in conflict with the Owner's standards, but that's my problem).

Thanks!

 

[petersonra]

The exhaust hood is not a duct. its connected to a duct, but itself is not a duct.
300.22 would seem to only prohibit the conduit being in a duct, but does not seem to prohibit it being inside an exhaust hood.