Plenum Rated Cable in EMT?

Status
Not open for further replies.

JFletcher

Senior Member
Location
Williamsburg, VA
Short run-down: The 1st floor ceiling space of a building is used for HVAC return. EMT conduit is run from non-plenum space, through the 'plenum', and ends in another non-plenum space.

Question: does the v/d/v/ cabling inside the EMT have to be plenum rated to be code compliant?
 

raider1

Senior Member
Staff member
Location
Logan, Utah
What type of cabling are you using?

For class 2 and 3 circuits 725.154(A) (2008 NEC) requires that cables installed in raceways in plenums and other spaces for enviromental air are required to be plenum rated.

Also communications cabling has the same requirement. Take a look at 800.154(A).

Chris
 

SEO

Senior Member
Location
Michigan
What type of cabling are you using?

For class 2 and 3 circuits 725.154(A) (2008 NEC) requires that cables installed in raceways in plenums and other spaces for enviromental air are required to be plenum rated.

Also communications cabling has the same requirement. Take a look at 800.154(A).

Chris
Chris I agree that 725.154(A) requires cables to be plenum rated if installed in plenums but the way the section is worded it is reffering to the duct, plenum and other space as the raceway. Emt installed in the plenum with non plenum rated conductors inside would be a seperate issue. It's allowed to install thhn conductors in emt is said space and they are not plenum rated.
 

JFletcher

Senior Member
Location
Williamsburg, VA
800.154A (2008 NEC) seems to contradict itself:

"Cables installed in ducts, plenums, and other spaces used for environmental air shall be Type CMP" - for free-run cable, this makes sense.

"Types CMP, CMR, CMG, CM, and CMX, and communications wire installed in compliance with 300.22 shall be permitted" - looks like I can run about anything in EMT, provided I also comply with other parts of the code (i.e., use CMR with a riser)

300.22 (C) (1) : "... other types of cables... shall be permitted to be installed in electrical metal tubing..."

Backs up 800.154A

but, the last sentence of 800.154A reads:

"Only type CMP cable shall be permitted to be installed in these raceways".

What am I missing?
 

tom baker

First Chief Moderator
Staff member
Short run-down: The 1st floor ceiling space of a building is used for HVAC return. EMT conduit is run from non-plenum space, through the 'plenum', and ends in another non-plenum space.

Question: does the v/d/v/ cabling inside the EMT have to be plenum rated to be code compliant?
This is not a plenum, but rather an air handling space. Wiring and conduit is almost never installed in a plenum, only when necessary.
There would be no confusion if we called the cable "air handling cable".
 

raider1

Senior Member
Staff member
Location
Logan, Utah
Chris I agree that 725.154(A) requires cables to be plenum rated if installed in plenums but the way the section is worded it is reffering to the duct, plenum and other space as the raceway. Emt installed in the plenum with non plenum rated conductors inside would be a seperate issue. It's allowed to install thhn conductors in emt is said space and they are not plenum rated.
I see a problem with the wording between 725.154(A) and 800.154(A)

In 725.154(A) the last sentence says "Only Type CL2P or CL3P cable shall be permitted to be installed in these raceways." I believe that "these raceways" is referring to listed plenum signaling raceways, and not chapter 3 raceways.

But 800.154(A) last sentence states "Only Type CMP cable shall be permitted to be installed in raceways." This sentence would include all chapter 3 raceways as well as listed plenum communications raceways.

Chris
 

jrdsg

Senior Member
cable in emt

cable in emt

I'm with Hal, I've never had an inspector question what kind of LV wiring was in an emt raceway in an air handling space or transiting a fire-rated partition.

I can see how the code is a little vague on the point, however...
 

JFletcher

Senior Member
Location
Williamsburg, VA
Thanks for the replies everyone.

Chris, it's cat5e, cat6, and RG6 cable, maybe some siamese as well.

"Emt installed in the plenum with non plenum rated conductors inside would be a seperate issue."

That is the issue. I see where you guys are coming from from a common sense standpoint - the cables are not in the air-handling space, only the EMT is, and a conduit is not a plenum or air-handling space. Common sense would say that if the EMT is run past the air-handling space on both ends that plenum rated cable should not be required.

Cabling a building with plenum rated cable is expensive if not required, and so is pulling out CM-whatever if CMP IS necessary.

"It's allowed to install thhn conductors in emt is said space and they are not plenum rated.

Good information to know. :cool:
 

raider1

Senior Member
Staff member
Location
Logan, Utah
For a Chapter 8 installation it seems clear that the cables installed in the EMT must be plenum rated. This might fly in the face of common sense but here is what 800.154 says:

800.154 Applications of Listed Communications Wires and Cables and Communications Raceways.

(A) Plenum. Cables installed in ducts, plenums, and other spaces used for environmental air shall be Type CMP. Abandoned cables shall not be permitted to remain. Types CMP, CMR, CMG, CM, and CMX and communications wire installed in compliance with 300.22 shall be permitted. Listed plenum communications raceways shall be permitted to be installed in ducts and plenums as described in 300.22(B) and in other spaces used for environmental air as described in 300.22(C). Only Type CMP cable shall be permitted to be installed in raceways.
Chris
 

raider1

Senior Member
Staff member
Location
Logan, Utah
Also here is what 820.154 says about CATV installations

820.154 Applications of Listed CATV Cables and CATV Raceways.

(A) Plenums. Coaxial cables installed in ducts, plenums, and other spaces used for environmental air shall be Type CATVP. Abandoned cables shall not be permitted to remain. Types CATVP, CATVR, CATV, and CATVX cables installed in compliance with 300.22 shall be permitted. Listed plenum CATV raceways shall be permitted to be installed in ducts and plenums as described in 300.22(B) and in other spaces used for environmental air as described in 300.22(C). Only Type CATVP cable shall be permitted to be installed in these raceways.
Chris
 

JFletcher

Senior Member
Location
Williamsburg, VA
Chris, 800.154 also says this:

"Types CMP, CMR, CMG, CM, and CMX and communications wire installed in compliance with 300.22 shall be permitted."

The way I read it, the last part of 800.154 applies to listed communications raceways. If I were to use something like Carlon Plenum Gard as a raceway, I would have to use plenum rated cable inside since ENT isn't listed in 300.22.
 

raider1

Senior Member
Staff member
Location
Logan, Utah
For cat5 wiring the wording at the end of 800.154, as written, would not permit you to install cat5 non-plenum rated cable in any raceway, not just communications raceways.

If you look at the differences between the 2 sections I posted I can see where for RG6 only the listed plenum CATV raceways would need to have plenum rated cables, but the wording is different for cat5.

Chris
 

raider1

Senior Member
Staff member
Location
Logan, Utah
For what it is worth there has been a code proposal for the 2011 code cycle to clarify section 800.154(A). I will be interested to see if the CMP will accept this porposal.

Chris
 
Status
Not open for further replies.
Top