Re: using CAT5 for smoke detectors

[jewellfish <jewellfish@xxxxxxxxx>]

Jim,

Actually, NFPA 72 (2002-4.4.4.4) does not directly address wire size
but redirects to NEC (NFPA 70).

Assuming we are talking power-limited circuits, NEC places the 18
gauge limit on single conductors.  If you are running THHN or
equivalent in raceway then the wire must be at least 18.  However, in
a multi-conductor cable, the minimum gauge is 26 gauge which would
mean that CAT 5 would be ok, in that regard.
Additionally, NEC (article 765) does certainly permit the substitution
of general purpose cable for fire rated cable, so that, unless local
amendments prevent it, regular CAT 5 could be used.

Not saying its a good idea, but it is allowed.