Fire Alarm classA raceway

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dnem

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A single break in class A fire alarm wiring knocks out the supervisory signal and sends the system into a trouble alert, but all the components continue to work because of the double feed. . But if you also get a break in either of the "backfeed" wires, you get a trouble alert and possible loss of component function. . So it would help if the 2 primary wires are separated from the 2 "backfeed" wires. . Then the possibility of simultaneous damage to both pairs is lessened.

Now I know that the backup or backfeed isn't required because it doesn't exist on a class B system. . But with class A, many people might assume they still have full component function and procrastinate repairs which might make a multiple break in a class A more serious than a break in a class B.

Is there a requirement in either NFPA70 or 72 that states that all 4 wires of a class A system can't be contained in the same raceway ?

David
 
dnem said:
Is there a requirement in either NFPA70 or 72 that states that all 4 wires of a class A system can't be contained in the same raceway ?

David
Click to expand...

NFPA 72 6.4.2.2.2 with exceptions for single devices etc.


Yes, the supply and return conductors can not be in the same raceway or cable there are no distance of separation requirements.

RI Fire alarm code modifies that with minimum separation distances of the cables or conduits.
 
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Jeremy,

Is the separate raceways for class A primary and backfeed wires concept found in a non-legally required industry standard such as TIA/EIA 568 ?
Is it just common industry practice that isn't a written standard anywhere ?

David
 
You have to question the whole class A theory,if we all agree the supply and return wires are not to be in the same raceway then why are the raceways not required to have a seperation?Also I have seen where a class A circuit that was destroyed take down the FACP regardless of whether it was the supply or return wires.
 
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