CMR Clarification and Opinion

[priszkid]

This is my first post, and am very thankful for all of the information here. I did a search for clarification, and couldn't find an answer, hence my question.

I ran into an interesting situation the other day, where I was required to have riser cable installed within a single story commercial building, per the AHJ. The cable installed (combination of cat5e {control} and 14-2 awg{speaker signal}) was run through pvc (sch 40) from various locations in a solid concrete slab and EMT through walls at ceiling height, with it's final destination stubbing out in an equipment rack. The rack is located in a small storage space above the main power for the building, non-plenum. The rack location did meet all of the requirements for working space, per the AHJ. The total height from slab to equipment rack was less than 11 feet and height from ceiling to rack was less than 6 feet (should that matter).

My question is, why would CMR be "required" since the space is not more than a single story (floor to floor), as i understand the code (800.179(B). I've yet to encounter this issue, so any clarification to help would be great.

Thanks in advance!
- Ray

 

[Smart $]

Is there some sort of floor or platform for this storage space where the equipment rack is located? If so, it does not matter that the building as a whole is considered single story. What matters is that you have two floors where the equipment rack is located... and going from grade-level slab to equipment rack is floor to floor.

Welcome to the forum :thumbsup:

 

[priszkid]

There is a floor for the equipment rack space and the rack was sitting flat on the floor in this space.

I did just take a call from one of my local inspectors who I asked when riser cable was needed. According to him, floor to ceiling in the same space, riser cable is not needed. Any time the cable goes to a different floor, floor 1 to floor 2, riser is required. This also includes basements. His words were from space to space, riser cable is needed.

 

[GoldDigger]

There is a floor for the equipment rack space and the rack was sitting flat on the floor in this space.

I did just take a call from one of my local inspectors who I asked when riser cable was needed. According to him, floor to ceiling in the same space, riser cable is not needed. Any time the cable goes to a different floor, floor 1 to floor 2, riser is required. This also includes basements. His words were from space to space, riser cable is needed.

If the upper space is not enclosed or has a grid floor, then the riser cable will not have any effect on fire spread. But if the "floor" of the space is effective as a fire stop and the storage area is not normally visible, then the inspector's requirement for CMR seems justified.

 

[hbiss]

I did just take a call from one of my local inspectors who I asked when riser cable was needed. According to him, floor to ceiling in the same space, riser cable is not needed. Any time the cable goes to a different floor, floor 1 to floor 2, riser is required. This also includes basements. His words were from space to space, riser cable is needed.

I agree. That said, we always stock and use riser listed cable since the price difference is almost nothing and you always wind up installing runs vertically through floors someplace. I do realize however that a combination cable such as what you are talking about might not be easily obtainable in riser. I would have likely used two separate cables, CAT5e and 14/2, both riser listed. Probably cheaper too.

-Hal

 

[priszkid]

thanks guys!