Your thinking is good, but there may be some differences in terminology. "Flame- resistant" or "fire-resistant" or "suitable for plenum installation" might be more common terms. There is a UL (Underwriters' Laboratories) classification for smoke generation, UL94 [??-not sure of number]. The NFPA (National Fire Protection Association) produces the NEC (National Electrical Code); there might be further information in this Code.

I have come across mineral insulated cable(pyrotenex) as well as pvc/pvc/cu cables in steel even in pvc conduit. It depends on the consultant but really it should be as per codes/standards.

Re: Pyrotenax cable.

After the fire in the Anglo / French channel tunnel the "Pyro" cable was still found to be serviceable. Can't get a better accolade than that!

Read article 760 of the National Electrical Code, NFPA 70.

In general, you are required to use cable or wire that is "listed" for fire safety use.

If you stick to FPL (free wired or in conduit), FPLR (riser cable), or FPLP (free wired in plenum areas) you will be OK if you size your cables for your load.

You can also use other listed single conductor wire.

Regardless of what wire/cable you select, you will still have to conform to all other requirements of NFPA 70, just with the added restraint of article 760.

Thanks. Your comment was useful. There is some disconnect between NFPA 70 and 72. NFPA 70 refers to NFPA 72 clauses 6.9.4.3 and 6.9.4.6. Chapter 6 does not exist in NFPA 72 2010. There is lot of overlap in the type of cables which can be used for Fire Alarm initiating circuits. It appears that it is not manadatory to use Circuit Integrity cables for such circuits. Is it not comprising with the safety of the installation?

You are not required to use fire system specific cable. You can for instance use THHN in conduit, THHN/THWN dual labeled for underground conduit, almost any TC (tray cable) rated cable or conductor, or direct burial cable.

The short answer is, for economy purposes, use the cables in my first post where appropriate. Select an option in this post for underground runs.

What should be the type(pvc/EMT,HD etc) of the conduit you mentioned used a)inside/outside buildings and b)underground?.

That depends on the project.

EMT is perfect indoors and outdoors (using rain-tight compression fittings when outdoors) in commercial applications, with PVC used underground.

In industrial applications, rigid steel conduit inside and out is recommended. Underground, I like direct burial cable in PVC.