NM Cable for Fire Alarm

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ryant35

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We have an application where we have an existing 120VAC smoke alarm circuit installed in a duplex residence with Romex 3#12 NM cable. I have found through my research that Romex cable is THHN but does the NM sheathing allow for open wiring inside walls? I would assume that we could because it is approved for 120VAC circuits to be run open, but the FD may require us to show it is allowed per NEC.

Thanks,

Ryan
 
ryant35 said:
We have an application where we have an existing 120VAC smoke alarm circuit installed in a duplex residence with Romex 3#12 NM cable. I have found through my research that Romex cable is THHN but does the NM sheathing allow for open wiring inside walls? I would assume that we could because it is approved for 120VAC circuits to be run open, but the FD may require us to show it is allowed per NEC.

Thanks,

Ryan
Click to expand...


Are you suggesting stripping the NM sheathing and running the conductors in the wall. That answer would be no as it is only rated as a complete cable.

I don't understand your question if my answer is not what you are looking for.
 
By "open wiring" are you talking about the NM being fished through the existing walls? If so generally there is no problem with that. But then you mention duplex residence. Does that have a bearing in this question? If the class of construction or a local ammendment prohibits NM then you very well may have a problem.

I think a clarification as to what you are asking is in order here.

-Hal
 
ryant35 said:
We have an application where we have an existing 120VAC smoke alarm circuit installed in a duplex residence with Romex 3#12 NM cable. I have found through my research that Romex cable is THHN but does the NM sheathing allow for open wiring inside walls? I would assume that we could because it is approved for 120VAC circuits to be run open, but the FD may require us to show it is allowed per NEC.

Thanks,

Ryan
Click to expand...

120 volt smoke alarms are not a FA system subject to article 760 rules, in most cases the 120 volt interconnected smoke alarms are required above and beyond an FA system. they will be wired by a chapter 3 wiring method.
 
ryant35 said:
We have an application where we have an existing 120VAC smoke alarm circuit installed in a duplex residence with Romex 3#12 NM cable. I have found through my research that Romex cable is THHN but does the NM sheathing allow for open wiring inside walls? I would assume that we could because it is approved for 120VAC circuits to be run open, but the FD may require us to show it is allowed per NEC.

Thanks,

Ryan
Click to expand...

Are you asking if Romex can be left exposed?

That would depend, generally NM requires a 15 min finish over it in finished spaces, and anywhere its subject to damage (except in a garage in MA :) )

334.10(3) Cables shall be concealed within walls, floors or ceilings that provide a thermal barrier of material that has a 15 minute finish rating as identified in listings of fire-rated assemblies
 
ryant35 said:
We have an application where we have an existing 120VAC smoke alarm circuit installed in a duplex residence with Romex 3#12 NM cable. I have found through my research that Romex cable is THHN but does the NM sheathing allow for open wiring inside walls? I would assume that we could because it is approved for 120VAC circuits to be run open, but the FD may require us to show it is allowed per NEC.

Thanks,

Ryan
Click to expand...

Read 334.10 Uses Permitted Page 70-185 /2008 NEC.
Read 334.12 Uses Not Permitted Page 70-186 /2008 NEC.
Read 300.11 (A)Through(C) Pages 70-131&132.
Read 334.112 Insulation 70-187.
Read 310.13(A) table pages 70-141 142 143.
Read 760 Fire Alarm Systems Page 70-625.
 
LEO2854 said:
Read 334.10 Uses Permitted Page 70-185 /2008 NEC.
Read 334.12 Uses Not Permitted Page 70-186 /2008 NEC.
Read 300.11 (A)Through(C) Pages 70-131&132.
Read 334.112 Insulation 70-187.
Read 310.13(A) table pages 70-141 142 143.
Read 760 Fire Alarm Systems Page 70-625.
Click to expand...

Again 120 volt battery backed up "Smoke Alarms" are not a "Fire Alarm" covered by article 760.

They are not in the NEC, except for the way we have to wire them, which is with any chapter 3 wiring method, if NM is used then you must follow the requirements for the installation of NM just like you would for any light outlet or receptacle you would wire with NM in your local codes.

You will find location requirements in the IBC not the NEC, the NEC will cover the wiring method only.
 
hurk27 said:
Again 120 volt battery backed up "Smoke Alarms" are not a "Fire Alarm" covered by article 760.

They are not in the NEC, except for the way we have to wire them, which is with any chapter 3 wiring method, if NM is used then you must follow the requirements for the installation of NM just like you would for any light outlet or receptacle you would wire with NM in your local codes.

You will find location requirements in the IBC not the NEC, the NEC will cover the wiring method only.
Click to expand...

iwire said:
I agree 100%.
Click to expand...

I agree 100% now that i have read ARTICLE 760 All the way through i stand corrected ,Thanks for pointing that out gents:roll:
 
Sierrasparky said:
Are you suggesting stripping the NM sheathing and running the conductors in the wall. That answer would be no as it is only rated as a complete cable.

I don't understand your question if my answer is not what you are looking for.
Click to expand...

No stripping, the electrical contractor installed the NM cable before the sheet rock and wired the smoke alarms together. Now the walls are complete and we need to use this cable for fire alarm.

hurk27 said:
120 volt smoke alarms are not a FA system subject to article 760 rules, in most cases the 120 volt interconnected smoke alarms are required above and beyond an FA system. they will be wired by a chapter 3 wiring method.
Click to expand...

I understand article 760, and that is how the system was originally installed, but the local fire department is asking for these smoke alarms to be replaced with smoke detectors that will be supervised and tested with the fire alarm system. This requirement only comes up when there is a requirement for a fire alarm system. We want to use the existing NM cable as fire wire and replace the 120VAC smoke alarms with addressable system detectors.

When I originally posted I left out the fire department's requirements to change the detectors thinking it would just be more info than what was needed, but I see now it would help explain what I am doing.
 
ryant35 said:
No stripping, the electrical contractor installed the NM cable before the sheet rock and wired the smoke alarms together. Now the walls are complete and we need to use this cable for fire alarm.



I understand article 760, and that is how the system was originally installed, but the local fire department is asking for these smoke alarms to be replaced with smoke detectors that will be supervised and tested with the fire alarm system. This requirement only comes up when there is a requirement for a fire alarm system. We want to use the existing NM cable as fire wire and replace the 120VAC smoke alarms with addressable system detectors.

When I originally posted I left out the fire department's requirements to change the detectors thinking it would just be more info than what was needed, but I see now it would help explain what I am doing.
Click to expand...


I would also check with you local AHJ on this, I think you might have to have both systems, separate of each other, a duplex is a one and two family dwelling, which should fall under IBC which will require the 120 volt with interconnect smoke alarms, there could be a day the FA system stops getting monitored and shut down, so the 120 volt units would still be in place to make sure there is an alarm per unit., I know thats the way it is here.

Fire marshals sometimes don't realize what there getting into, when they make these requirements.
 
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