Wire Requirements for 70 Volt Fire Alarm Speaker Circuits

Status
Not open for further replies.
J

JohnPC

Member
Location
Bergen County, New Jersey
What kind of wired would be required for a 70 Volt speaker circuit being installed for a voice evacuation fire alarm system in a high rise residential building in NJ? Is FPL wire permitted or would it have to be armored cable such as MC?

Thanks!
 
JohnPC said:
What kind of wired would be required for a 70 Volt speaker circuit being installed for a voice evacuation fire alarm system in a high rise residential building in NJ? Is FPL wire permitted or would it have to be armored cable such as MC?

Thanks!
Click to expand...

Specifications aside, FPL is perfectly suitable. However, my advice is to run FPLP. You'll need it anyway if you run it in a drop ceiling used for "other environmental air", and if you accidently use it as a riser between floors your labor costs to re-run will eat up any savings in material. Keep nothing but FPLP on site and you can't make a mistake.

Please note that if the building is going to use "floor above, floor below, floor of incidence" type notification instead of evacuating the entire building on alarm you will need CI or equal for the riser between floors. Since UL pulled the listing for all CI and CIC cables, you'll be left with MI, and that just bites.
 
CI appears to be back

CI appears to be back

gadfly56 said:
Specifications aside, FPL is perfectly suitable. However, my advice is to run FPLP. You'll need it anyway if you run it in a drop ceiling used for "other environmental air", and if you accidently use it as a riser between floors your labor costs to re-run will eat up any savings in material. Keep nothing but FPLP on site and you can't make a mistake.

Please note that if the building is going to use "floor above, floor below, floor of incidence" type notification instead of evacuating the entire building on alarm you will need CI or equal for the riser between floors. Since UL pulled the listing for all CI and CIC cables, you'll be left with MI, and that just bites.
Click to expand...

http://www.ul.com/global/eng/pages/offerings/perspectives/regulator/fire/cables/
 
Also, check with the specifications on the 70 volt audio system. Some older systems were non power limited and you would need to use NPLFP, NPLFR, or NPLF. Some 70 volt audio is power limited and you can use the standard FPL, FPLR and FPLP unless you need the 2 hour fire rating.
 
dhalleron said:
Also, check with the specifications on the 70 volt audio system. Some older systems were non power limited and you would need to use NPLFP, NPLFR, or NPLF. Some 70 volt audio is power limited and you can use the standard FPL, FPLR and FPLP unless you need the 2 hour fire rating.
Click to expand...

Good point. In fact, newer systems may also be non-power limited. Siemens has a module, the ZAM-180, that provides non-power limited audio output. Their wiring manual makes the point that you can't run it with anything else related to the fire alarm system. On the other hand, their ZAC-40 audio module has a power limited output.
 
For a large system, the required power for all of the speakers could push the necessary output above the power limit.
To accommodate that situation with power limited amps would require multiple speaker circuits, each with its own amplifier.

Tapatalk!
 
Thanks for the input guys! My main concern was whether armored cable became necessary because of the higher voltage. I didn't think so, but I always like to be sure. The amp's outputs are in fact power limited. I always use FPLP to avoid issues.
 
Another question while I have you guys all on this topic. Are voltage drop calculations typically done for speaker circuits like they are for NAC circuits? I've seen multiple charts giving amperage/guage to distance lengths for speaker circuits. None of the manufacturers have voltage drop calculators for speaker circuits. Is it mostly a matter of using the table to ensure that you're not running a longer circuit than is shown on such a chart for the wattage and guage of the wire?
 
GoldDigger said:
For a large system, the required power for all of the speakers could push the necessary output above the power limit.
To accommodate that situation with power limited amps would require multiple speaker circuits, each with its own amplifier.

Tapatalk!
Click to expand...

Annnnd, that's exactly what we do. Last voice system I did had about 25 amplifier cards.
 
JohnPC said:
Another question while I have you guys all on this topic. Are voltage drop calculations typically done for speaker circuits like they are for NAC circuits? I've seen multiple charts giving amperage/guage to distance lengths for speaker circuits. None of the manufacturers have voltage drop calculators for speaker circuits. Is it mostly a matter of using the table to ensure that you're not running a longer circuit than is shown on such a chart for the wattage and guage of the wire?
Click to expand...

The Siemens wiring guide has a table that gives the maximum resistance for any given voltage and wattage combination. Just stay under that and you should be good. For example, if the ZAC-40 is loaded to 30 watts (about the maximum it should be), then on the 70.7 volt configuration you are allowed a maximum 32 ohms. If you use 14 AWG, they have another table that gives the resistance as 3.07 ohms/1000 feet at 75C. You could then wire that speaker zone basically to 10,000 feet, probably far longer than you'd want to wire a single speaker zone.
 
Status
Not open for further replies.
Top