Fire Alarm Code Q

[mstrlucky74]

For a Class A system where you have a return loop is it code to keep the supply and return in separate conduits if the fire alarm cable is all in conduit? Thanks.

 

[infinity]

For a Class A system where you have a return loop is it code to keep the supply and return in separate conduits if the fire alarm cable is all in conduit? Thanks.

Yes, I believe that the exception is 10' up and down to a device.

 

[gadfly56]

Yes, I believe that the exception is 10' up and down to a device.

The full text on that:

23.4.2.2* Class A and Class X 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 be permitted
in the same cable assembly (i.e., multi-conductor cable), enclosure,
or raceway only under the following conditions:

(1) For a distance not to exceed 10 ft (3.0 m) where the outgoing
and return conductors enter or exit the initiating
device, notification appliance, or control unit enclosures

(2) For single raceway drops to individual devices or appliances

(3) For single raceway drops to multiple devices or appliances
installed within a single room not exceeding
1000 ft2 (93 m2) in area

This is straight from the 2010 edition of NFPA 72, and it's not modified by the Q appendix.

 

[mstrlucky74]

Thanks

 

[steve66]

If I could add a question onto this thread:

Is there anything that states when a class A or class X system is required?

 

[gadfly56]

If I could add a question onto this thread:

Is there anything that states when a class A or class X system is required?

No, that's strictly a design decision, unless the local jurisdiction has chimed in with amendments. Usually called for in critical installations by various government entities for things such as train stations, bus stations, airports, etc.