Fire Alarm cable according to NEC

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love9099

love9099

Member
Location
Salt Lake City
We have ran into several issues with Fire Alarm Cable when it comes to AHJs, Electrical Contractors and Specifications. Some of the Specs require THHN for fire alarm. I don't know if the Engineers don't understand that Non-Power Limited Fire Alarm Circuits are High voltage and that Power Limited are low voltage or not. Is this correct? NEC (NFPA 70) states that for POWER LIMITED fire alarm circuits that FPL, FPLR, FPLP and CMP wire is approved. We have some Contractors that install THHN for all their fire alarm, I understand that THHN is rated at 600 V and should exceed the requirements for fire alarm although THHN is listed for NON-POWER LIMITED in NEC it does not say you can use it for Power Limited. Am I missing some specific code reference? We have had fire marshals that have had issues with this. Normally I don't mind if an Electrical Contractor run THHN and the AHJ is ok with it. What concerns us more is when they install THHN when we clearly recommended FPL 18g/2c for an addressable loop in order to have the correct twists for data transfer. I understand all of us should install the correct cable to meet both the code and the manufactures recommendations. We had an AHJ make the Contractor pull out THHN that they ran for Horn/strobes because he said he wanted FPL and it was in conduit. I thought this was a bit much. Please let me know how you deal with these issues. I try to make it clear to the contractors the manufactures recommendations along with the code reference up front.
 
raider1

raider1

Senior Member
Staff member
Location
Logan, Utah
THHN that is part of a recognized wiring method can be used for power limited fire alarm circuits. See 760.130(A) in the 2008 NEC.

Chris
 
R

Rob454

Member
love9099 said:
We have some Contractors that install THHN for all their fire alarm, I understand that THHN is rated at 600 V and should exceed the requirements for fire alarm although THHN is listed for NON-POWER LIMITED in NEC it does not say you can use it for Power Limited. Am I missing some specific code reference? We have had fire marshals that have had issues with this. Normally I don't mind if an Electrical Contractor run THHN and the AHJ is ok with it. What concerns us more is when they install THHN when we clearly recommended FPL 18g/2c for an addressable loop in order to have the correct twists for data transfer. I understand all of us should install the correct cable to meet both the code and the manufactures recommendations. We had an AHJ make the Contractor pull out THHN that they ran for Horn/strobes because he said he wanted FPL and it was in conduit. I thought this was a bit much. Please let me know how you deal with these issues. I try to make it clear to the contractors the manufactures recommendations along with the code reference up front.
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The THHN should NEVER be used in place of the SLC wire. As for the AHJ making you pull out the THHN and install FPL it all depends on what was spec out on the job. When you read the spec book what did it specify for wire cable type for NAC circuits? Usually the first thing I do is grab the spec book and read and highlite everything pertaining to me. then I make sure all my wire on the job corresponds with what the specs ask. all other wire is sent back to the shop.
The AHJ/fire marshall can demand all they want but if the contractor installed what was spec'ed out as far as specific wire then it all falls back on the architect or whoever designed the plans. The contractor is only gonna install what the architect tells him to install. if the contractor takes it upon himself to run what he pleases then yeah he will probably get popped by some inspector
 
F

firealarmguy

Member
Rob454 said:
The THHN should NEVER be used in place of the SLC wire. As for the AHJ making you pull out the THHN and install FPL it all depends on what was spec out on the job. When you read the spec book what did it specify for wire cable type for NAC circuits? Usually the first thing I do is grab the spec book and read and highlite everything pertaining to me. then I make sure all my wire on the job corresponds with what the specs ask. all other wire is sent back to the shop.
The AHJ/fire marshall can demand all they want but if the contractor installed what was spec'ed out as far as specific wire then it all falls back on the architect or whoever designed the plans. The contractor is only gonna install what the architect tells him to install. if the contractor takes it upon himself to run what he pleases then yeah he will probably get popped by some inspector
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Another thing to consider is what conduit are you using?

A long time ago in NYC, 120V ("non power limited") wiring in THHN had to be in rigid galvanized steel. If you used the approved 150 degree Celsius NYC teflon fire alarm wire, you could do it in EMT. In 2003, this rule was relaxed to allow THHN in EMT.
 
love9099

love9099

Member
Location
Salt Lake City
THHN and FPL

THHN and FPL

Ok, I get a contractor saying never use THHN on an SLC loop, then I get another contractor that says it is done all the time. Then I get a NEC code reference to 760.130 saying this allows you to use THHN on Power Limited Fire Alarm Circuits so I looked it up and found that on the load side of the Power Limited Fire Alarm power source you can use wiring methods and materials in reference to 760.46 which addresses installation of non-power limited fire alarm circuits (high voltage) then there is a reference in 760.53 that states that multiconductor non-power limited fire alarm cables (high voltage) that meet the requirements of 760.176 shall be permited to be used on fire alarm circuits operating at 150 volts or less (which is POWER LIMITED)and shall be installed in accordance with 760.53 (A) (1), (A) (2) and (A) (3) so then we go to 760.176 and we find a chart that goes back and lists Multiconductor cables and their acceptable subsitutions which are CMP or FPLP or CMR or FPLR or CMG/Cm or FPL so the CMP, CMR and CMG/CM are commmucations wire and cables and the FPL, FPLR and FPLP are Fire Alarm Cables. FPL is general use, FPLR is riser wire able to hold it's own weight in a shaft and avoid the spread of fire up the wire and FPLP is plenum rated that meets or exceeds the other requirements and does not put off as much toxic fumes. Then you find more detailed information in 760.176(G) about the fire wire on page 70-632 so the reference for using NPLFA cables on PLFA is 760.53 as long as it meets the 760.176 but I still don't find THHN listed but apart from that I understand the comment about installing what was specified and on the case where the AHJ made them take it out the drawings clearly listed FPL, FPLR or FPLP cable and THHN was installed although I did not argue because it was for horn/strobes on that one and they would work just fine. The conduit they installed them in was EMT not ridged. It is difficult when you install a fire system with data transfer where you need the certain twists per foot (normally 12) and an engineer specifies THHN which does not meet manufacturer recomendations and ends up causing issues. Why would a contractor install THHN when FPL is less expensive and encased in a jacket already with 2 conductors and they pull it off separate spools? Just because they have it on the shelf? :-?
 
D

DHkorn

Member
My 2 cents

My 2 cents

Our local AHJ requires conduit to prevent injury to conductors. So we do that all the time.
The NEC allows class II circuits to be re-classified as class I by installing them with THHN in conduit, if allowed by the product 'wiring compatability guide' (or similar document); it's one of the three controllers; (the other two are the local AHJ or the specs).
 
J

jconsiglio

New member
Slightly off topic I know, but I have a fire alarm cable specification I am trying to meet. There are 2 requirements that are in question:

1) Limited combustible FHC 25/50 CMP
2) Smoke developed rating not to exceed 50 when tested in accordance with ASTM E-84


Any suggestions?
 
M

MisterCMK

Member
Location
Twin Cities, MN
love9099 said:
Ok, I get a contractor saying never use THHN on an SLC loop, then I get another contractor that says it is done all the time. Then I get a NEC code reference to 760.130 saying this allows you to use THHN on Power Limited Fire Alarm Circuits so I looked it up and found that on the load side of the Power Limited Fire Alarm power source you can use wiring methods and materials in reference to 760.46 which addresses installation of non-power limited fire alarm circuits (high voltage) then there is a reference in 760.53 that states that multiconductor non-power limited fire alarm cables (high voltage) that meet the requirements of 760.176 shall be permited to be used on fire alarm circuits operating at 150 volts or less (which is POWER LIMITED)and shall be installed in accordance with 760.53 (A) (1), (A) (2) and (A) (3) so then we go to 760.176 and we find a chart that goes back and lists Multiconductor cables and their acceptable subsitutions which are CMP or FPLP or CMR or FPLR or CMG/Cm or FPL so the CMP, CMR and CMG/CM are commmucations wire and cables and the FPL, FPLR and FPLP are Fire Alarm Cables. FPL is general use, FPLR is riser wire able to hold it's own weight in a shaft and avoid the spread of fire up the wire and FPLP is plenum rated that meets or exceeds the other requirements and does not put off as much toxic fumes. Then you find more detailed information in 760.176(G) about the fire wire on page 70-632 so the reference for using NPLFA cables on PLFA is 760.53 as long as it meets the 760.176 but I still don't find THHN listed but apart from that I understand the comment about installing what was specified and on the case where the AHJ made them take it out the drawings clearly listed FPL, FPLR or FPLP cable and THHN was installed although I did not argue because it was for horn/strobes on that one and they would work just fine. The conduit they installed them in was EMT not ridged. It is difficult when you install a fire system with data transfer where you need the certain twists per foot (normally 12) and an engineer specifies THHN which does not meet manufacturer recomendations and ends up causing issues. Why would a contractor install THHN when FPL is less expensive and encased in a jacket already with 2 conductors and they pull it off separate spools? Just because they have it on the shelf? :-?
Click to expand...

There is nothing wrong with installing THHN in EMT for fire alarm. Not all systems require twisted shielded wire for the data loop. What does the manufacturer of the fire alarm panel say is required?
 
O

olc

Senior Member
This is a good topic. Here are some questions:
Lets say in a big box store - power limited cables can be run along bar joist which will protect them but should be in conduit down to wall mounted devices?
Who is the AHJ that you have had require conduit - town code inspector? fire marshall? electrical inspector?
Is there any non-power limited circuit in a typical fire alarm system? security system? low voltage door bell? PA system? (I just want to make sure I am not missing something)
 
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