300.22 (b)

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wireguy8169

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Southern Maine
Kinda have two questions

1. is there a Non metallic raceway that is plenum rated and if so and you ran it in a 300.22 (B) location would the conductors ran inside of this race way also need to be plenum rated?

2. What makes a space above a ceiling or below a floor an enviromental air space, I am thinking if there is an opening between rooms (either above the ceiling or below a floor it would fall under 300.22(b), but if there was no open space between areas (say office to office) it would then "not" classified as a 300.22 (B) location hencee no need for plenum rated wire or raceway.

This is not an installation issue or anything at this time just doing some code course work. Hope the question makes sense.

Thanks
 
wireguy8169 said:
Kinda have two questions



2. What makes a space above a ceiling or below a floor an enviromental air space, I am thinking if there is an opening between rooms (either above the ceiling or below a floor it would fall under 300.22(b), but if there was no open space between areas (say office to office) it would then "not" classified as a 300.22 (B) location hencee no need for plenum rated wire or raceway.


Thanks
Click to expand...

As far as this part, a good rule of thumb is if there is solid return air duct work it is not a plenum. If there are only grills in the ceiling and the air flows through the space it is a plenum.
 
That is what I always thought, but seems to me there is a difference between a plenum and what 300.22 defines as an enviromental air space (which is what I was wondering...)
but I was watching the Mike Holt video segment on it and the way they said it I got that it doesnt matter if there are "physically constructed ducts or plenums" (this is what one of the inspectors inthe video refered to it as) it could still be considered an enviromental air space, thats what got me to my question. This is the video link...
http://www.youtube.com/user/MikeHoltNEC#p/u/3/hD-RdBAFbzg

or you go to the video/graphics tab and go under 2008 and about 2/3rds way down the page is the video link for 300.22 check it out if you like an please give any feed back....

Thanks
 
I just watched the video again and what I am getting is that if the air flow above the ceiling or below the floor is restricted to that area then 300.22(B) would not apply but if the air flow was not "restricted" to that one area and even if there were constructed plenum and ducts you would need to adhere to 300.22(B). Any input either way is appreciated...
 
wireguy8169 said:
Kinda have two questions

1. is there a Non metallic raceway that is plenum rated and if so and you ran it in a 300.22 (B) location would the conductors ran inside of this race way also need to be plenum rated?
Click to expand...
The is non-metallic plenum raceway but you cannot use it in 300.22(B) applications. Its use is limited to 300.22(C) applications and even in those applications you still have to use "plenum" rated cables.

2. What makes a space above a ceiling or below a floor an enviromental air space, I am thinking if there is an opening between rooms (either above the ceiling or below a floor it would fall under 300.22(b), but if there was no open space between areas (say office to office) it would then "not" classified as a 300.22 (B) location hencee no need for plenum rated wire or raceway.
Click to expand...
If the space above the ceiling is used for the return air is is a 300.22(C) application. If both the supply and return air are in ducts, it is not anything more than space above a ceiling. The open space above a ceiling can never be a 300.22(B) space.
 
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