wbb
Member
- Location
- brockton MA 02302
what determines when fire alarm cable shall be in some kind of metal race way like emt or mc cable
wbb
- Thread starter wbb
- Start date
- Status
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
One reason would be when the ceiling is a plenum
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Or other environmental air handling space....
But if you are using fire alarm cable plenum rated fire alarm cable is available, right?.
So would it be more accurate to say "in a plenum or environmental space when using non-plenum rated cable"?
Conduit would also be required if using single conductor wires instead of cable. (Something like THHN/THWN).
And then there is the whole power limited, non-power limited mess. If I understand it correctly, if you are using power limited, conduit would not be required, but for non-power limited, conduit MAY be required.
So would it be more accurate to say "in a plenum or environmental space when using non-plenum rated cable"?
Conduit would also be required if using single conductor wires instead of cable. (Something like THHN/THWN).
And then there is the whole power limited, non-power limited mess. If I understand it correctly, if you are using power limited, conduit would not be required, but for non-power limited, conduit MAY be required.
Carultch
Senior Member
- Location
- Massachusetts
Another reason is if it is in an environment where it can be interpreted as "subject to physical damage", in which case you might need IMC or RMC. It is difficult to know exactly what is, and isn't, "subject to physical damage". One example is if you have a warehouse where it is subject to accidental forklift traffic.
gadfly56
Senior Member
- Location
- New Jersey
- Occupation
- Professional Engineer, Fire & Life Safety
Non-Power Limited Fire Alarm (NPLFA) circuits are wired according to Chapter 3 methods, so look to those limitations and requirements. Power Limited Fire Alarm (PLFA) circuits are wired according to 760.130(B) et seq and DON'T require Chapter 3 methods unless otherwise specifically called for.
The only time metal raceway is specifically called for is when passing through a floor or wall, and then to a height of 2.1m or 7ft (760.130(B)(2)). This applies to PLFA circuits. There is a general requirement to protect cable from damage, but it still doesn't mandate metallic raceway or MC.
Otherwise it's entirely driven by the spec/customer requirements and local amendments to NFPA 72 or 70 (NYC is famous for this).
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