fire alarm cable

[brett711]

in a plenum rated ceiling, do all the low voltage cables wired free air have to be plenum, will the inspector ?? it, if the exisitng is non plenum

 

[peter d]

Yes to the first question, yes to the second if the inspector is sharp and reads the writing on the cables

 

[DUCKMAN]

in a plenum rated ceiling, do all the low voltage cables wired free air have to be plenum, will the inspector ?? it, if the exisitng is non plenum

If you are running cable in an "other space for environmental air", what most people would call a plenum ceiling, the cable must be plenum rated. A plenum rated cable will produce less smoke in a fire. This prevents comtaminating the return air supply with smoke, possibly engangering the occupants of other areas of the building during a fire. Plenum cable also exceeds the rating of riser cable, so it will also not allow vertical flame spread.

Any inspector worth his salt will catch the use of non-rated cables. The expense of rewiring does not justify the savings of using non-rated cables. Nevermind the liability if there is a fire. Factor in the cost of the more expensive cable from the start, and stick with it.

 

[DHkorn]

Plenum vs. Other Spaces for environmental air

Plenum vs. Other Spaces for environmental air

I've spent 30 years doing electrical work in the Country of Chicago. When I first went out on my own I couldn't figure out why there was no 'plenum boxes' or 'plenum covers' in any of the national catalogs. Then I cracked open the NEC and discovered that what I called a plenum and what they called a plenum were two diffrent things.

Per the NEC, for most of us working in ceilings we are in 'other spaces for environmental air'. And only very rarely are we in plenums.

The best explaination is in the NEC handbook.