NEC 760.136

Lenz81

Member
Location
Alaska
NEC 760.136 does not allow Power limited fire alarm ciruits to be run with Light , power.... in same raceway , but what about Power for fire Control Panel itself ? Can it be run with Power Limted Fire Alram cables ?
 

nhfire77

Senior Member
Location
NH
NEC 760.136 does not allow Power limited fire alarm ciruits to be run with Light , power.... in same raceway , but what about Power for fire Control Panel itself ? Can it be run with Power Limted Fire Alram cables ?
No.

I dont have my NEC open but it must be separated, there is an exeception for devices that have only one opening.

Within an enclosure you must maintain 1/4" separation between power limited/ non power limited.

FYI: battery leads are nonpower limited as well.
 

Lenz81

Member
Location
Alaska
thanks , Can i run my Power cable for Fire system with another Power cable from a different system ? I am being told everything related to fire system should stay in its own dedicated raceway but i cannot find anything on NEC .
 

nhfire77

Senior Member
Location
NH
thanks , Can i run my Power cable for Fire system with another Power cable from a different system ? I am being told everything related to fire system should stay in its own dedicated raceway but i cannot find anything on NEC .
when you say power cable, what do you mean?

A facp needs a chapter 3 wiring method (EMT, FMC, Rigid, PVC etc)

Job specs and local amendments aside you can mix line voltage circuits in the same conduit as long as its a dedicated circuit.

Personally, if the choice available I would pipe in a dedicated circuit in a dedicated piece of EMT/Rigid or MC if concealed.
 

rcwilson

Senior Member
Location
Redmond, WA
lenz- Per your PM I think your question is:

Is the 120V power wiring to a Fire Alarm Panel with a PLFA power supply (24VDC with battery) considered part of the Fire Alarm Circuit?

If it is part of the FA circuit, it can't be in a raceway with non-FA power conductors.

If it is not a FA circuit per the definition of "Fire Alarm Circuit", it can share araceway with other power conductors.

I think this is how your installation is put together:

120V power from a UPS panel to a local Fire Alarm panel with a listed, integra,l 24VDC, PLFA power supply + battery.

The local sensing/alarm devices are wired to the local FA panel with PLFA cables in dedicated raceways.

An alarm signal from this local FA Panel to the plant's Main FA Panel is in dedicated raceway using NPLFA/PLFA rated cable. Circuit is considered as PLFA.

Per 760.136, the 120V power cable can't go in the PLFA raceway back to the Main Panel area.

760.127 "Wiring Methods on Supply Side of the PLFA" says it has to be installed per Part II.

Part II, 760.48 (B) says "Power-supply and fire alarm circuit conductors shall be permitted in the same.....raceway only where connected to the same equipment. " Unrelated power circuits are not allowed with fire alarm circuits.

The definition of Fire Alarm Circuit includes the "portion of the wiring system between the load side of the overcurrent device or the power-limited power supply?."

I think the 120 V power is not part of the Fire Alarm Circuit because it is on the supply side of the power limited power supply. The FA circuit starts at the power supply load terminals per the "or" in the definition.

If my interpretation is correct, the dedicated 120V power cable could share a conduit with non-FA power circuits. I don't think it would diminish the integrity of the FA circuit. If the 120V circuit fails for any reason, the battery back up takes over and the trouble alarm goes off.

Could the Fire Alarm experts weigh in and tell us if my interpretation is correct or faulty?

Thanks,
 

rcwilson

Senior Member
Location
Redmond, WA
A little background information. The local fire alarm panel monitors an unoccupied standby (not emergency) diesel generator enclosure a ways away from the main building. Raceways are in an underground duct bank. Normal 120V power is available at the enclosure but client requires UPS power to all fire systems (even though all fire systems have battery back up rated longer than UPS).

UPS power has to go into existing UG conduits or expensive new UG raceway. Power to FA panels is by different sub-contractor than the fire alarm system. That complicates liability.
 
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