Exhaust Hood connection

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Gategator37

Senior Member
I am wiring up an exhaust hood and the 14x14 duct is covering the normal knockout to this location. Can liquidtite or any other raceway be installed in this duct to feed the hood? or do I have to come out of the roof and run liquidtite to the hood from the outside?

The hood is round (i'm sure you have all seen them before) and are a pain to get into from the outside.

Please help and Thank you.
 

Gategator37

Senior Member
I am having a horrible day explaining things. This is all in relation to feeding the exhaust fan that is located on the roof. The hood really has nothing to do with it. The exhaust fan connection is located within the 14x14 ductwork. So I think we make the connection to the exterior of the exhaust fan. Is there any code requirements stopping me from running it in the ductwork? This is exhausting the cooktop hood.
 

220/221

Senior Member
Location
AZ
I wouldn't even consider doing it.

As far as NEC? I have no idea. They allow you to do lots of bad/crazy stuff :D
 

MarkyMarkNC

Senior Member
Location
Raleigh NC
The round exhaust hoods at restaurants where the top unlatches and is on a hinge? I've usually just penetrated the roof with emt through a witches hat, and then brought carlon over to the JB.

On the make-up air units, there is sometimes room in the curb to come up right next to the duct, but usually not in the exhaust units.
 

acrwc10

Master Code Professional
Location
CA
Occupation
Building inspector
The NEC doesn't directly say you cant do it but installation instructions on the unit are going to send you to the mechanical code and there you will find it is not allowed.
 

renosteinke

Senior Member
Location
NE Arkansas
A look at NFPA 96 -which covers such systems- ought to make clear that you can't do that - even though the fans are conveniently set up to allow you to do just that.

The NEC specifically bans any wiring from inside the hood. I would consider that to include the ducting, right up to the fan blades.

You have a few issues to consider. First off, sanitary requirements are harder to meet when there are additional places to trap grease. Secondly, the hood cleaner -if he's conscientous- will want to actually remove the fan and set it aside as he does his thing.

(I know, the fans often are hinged for cleaning, but I've seen quite a few where the cleaner removed the hinges).
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
I've gotten roof fans power by hole-sawing through the side of the curb from the roof, lowering a pullstring or fishtape through the hole, and hoisting up the end of MC with an angle connector on it.

Then, I screw a rectangular WP box with a threaded 1/2" KO on the back, and either put a disco switch there, or make joints with a blank plate, and run the wires in liquid-tight to the fan or a disco.

Added: I also apply a ring of silicone to the back of the box for rain-tightness.
 
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