Fire Alarm: Class A Circuit Seperation

Status
Not open for further replies.

TLBryant

Member
Location
West Virginia
Is there a code of standard that states a minimum distance of separation for outgoing and return conductors for Class A Fire Alarm Circuits?

I have checked NFPA72 6.4.2.2.2, 6.4.3.1-6.7

Outside of requiring the outgoing and return conductors to be routed separately, NFPA72 does not state minimum distances and pretty much says it is up to the designer/installer and to take the use of the building and hazards into consideration when routing the signaling path.

Is there another document or code to reference? NFPA70(NEC) only sets requirements for separation from non-fire alarm circuits 760.136
 

6.4.2.2.2* All styles of Class A circuits using physical conductors
(e.g., metallic, optical fiber) shall be installed such that
the outgoing and return conductors, exiting from and returning
to the control unit, respectively, are routed separately. The
outgoing and return (redundant) circuit conductors shall not
be run in the same cable assembly (i.e., multi-conductor
cable), enclosure, or raceway.

Exception: The outgoing and return (redundant) circuit conductors
shall be permitted to be run in the same cable assembly, enclosure, or
raceway under any of the following conditions:
(1) For a distance not to exceed 3 m (10 ft) where the outgoing and
return conductors enter or exit the initiating device, notification
appliance, or control unit enclosures
(2) Single conduit/raceway drops to individual devices or appliances
(3) Single conduit/raceway drops to multiple devices or appliances
installed within a single room not exceeding 92.9 m​
2 (1000 ft2)

in area.

A.6.4.2.2.2​
A goal of 6.4.2.2.2 is to provide adequate separation
between the outgoing and return cables. This separation
is required to help ensure protection of the cables from physical
damage. The recommended minimum separation to prevent
physical damage is 305 mm (1 ft) where the cable is installed
vertically and 1.22 m (4 ft) where the cable is installed

horizontally.
The appendix is not enforceable, but it helps understand the intent.
Generally, Class A circuits are required by specification/Contract only, so hopefully there is further description in that project specific document, but nothing enforceable in a code/standard.
 
I am on my phone right now, but I believe it is specifically listed in 72. One foot vertical four feet horizontal. At least that's what I would do. Anyone else out there feel free to correct me.
 
Status
Not open for further replies.
Top