ron
Senior Member
- Location
- New York, 40.7514,-73.9925
Has anyone checked a fire alarm installation to verify that the numbers of wires/cables do not exceed 40% conduit fill and are detrated based on # of conductors/cables?
I have run into arguments regarding this topic. I'm mostly interested in the conduit fill, as the fire alarm circuits are relatively low amperage. Please verify my logic for this requirement.
The situation is non-power limited fire alarm circuits installed in EMT.
760.28(A) takes us to 300.17 for fill and 300.15(B)(2)(a) for derated.
300.17 takes us to 358.22 for fill and limit us to 40% for more than 2 conductors/cables.
300.15(B)(2)(a) is invoked if the circuit carries more than 10% continuous load (which is possible) and has severe deratings.
I have run into arguments regarding this topic. I'm mostly interested in the conduit fill, as the fire alarm circuits are relatively low amperage. Please verify my logic for this requirement.
The situation is non-power limited fire alarm circuits installed in EMT.
760.28(A) takes us to 300.17 for fill and 300.15(B)(2)(a) for derated.
300.17 takes us to 358.22 for fill and limit us to 40% for more than 2 conductors/cables.
300.15(B)(2)(a) is invoked if the circuit carries more than 10% continuous load (which is possible) and has severe deratings.