Layout of Fire Detection Distribution System
- Thread starter eeee
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- Illinois
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- retired electrician
Re: Layout of Fire Detection Distribution System
Don
[ November 03, 2005, 10:41 AM: Message edited by: don_resqcapt19 ]
Modern addressable ones can handle a lot more dirt than the older ones. They adjust for the dirt build up, and when they get too dirty, give a trouble alarm, not a fire alarm.
Don
[ November 03, 2005, 10:41 AM: Message edited by: don_resqcapt19 ]
Re: Layout of Fire Detection Distribution System
It sounds like you are new to the fire alarm world. May I suggest the following:
1. Find a fire alarm dealer (Notifier, Simplex[ugh], etc.) You can buy Firelite equip direct.
2. Ask him to design and offer an 'equipment only' quote on a system that will satisfy the code in your area.
3. You mention "Fire Department" frequently. Can they have any whim that they want? Or are they bound to an NFPA and/or local code like the rest of us?
Believe me, you want an addressable system.
Even if they do sprinklers instead of a fire alarm, there will likely be a small monitoring panel for the sprinkler system.
Be sure that your design includes provision for ADA requirements. (heights of devices like A/V units and pull stations)
It sounds like you are new to the fire alarm world. May I suggest the following:
1. Find a fire alarm dealer (Notifier, Simplex[ugh], etc.) You can buy Firelite equip direct.
2. Ask him to design and offer an 'equipment only' quote on a system that will satisfy the code in your area.
3. You mention "Fire Department" frequently. Can they have any whim that they want? Or are they bound to an NFPA and/or local code like the rest of us?
Believe me, you want an addressable system.
Even if they do sprinklers instead of a fire alarm, there will likely be a small monitoring panel for the sprinkler system.
Be sure that your design includes provision for ADA requirements. (heights of devices like A/V units and pull stations)
Re: Layout of Fire Detection Distribution System
The issue with a trouble alarm on a smoke detector is that expensive maintenance is then required. That is why sprinklers are suggested since a riser and fire pump already exist and it costs the same as an addressable fire detection system even considering that a panel is required for the sprinkler system also.
Interestingly though, it seems those sprinkler heads need maintenance also. The maintenance issue should not be a consideration with smoke detectors/sprinklers maybe???
Incidentally, I am looking in to someone's comment that the NFPA code does not require conduit for the fire cable that is hung in the high rafters. I can not possibly believe this.
That does not even pass the logic test. There would no longer be any fire detection if the cables burned first.
The issue with a trouble alarm on a smoke detector is that expensive maintenance is then required. That is why sprinklers are suggested since a riser and fire pump already exist and it costs the same as an addressable fire detection system even considering that a panel is required for the sprinkler system also.
Interestingly though, it seems those sprinkler heads need maintenance also. The maintenance issue should not be a consideration with smoke detectors/sprinklers maybe???
Incidentally, I am looking in to someone's comment that the NFPA code does not require conduit for the fire cable that is hung in the high rafters. I can not possibly believe this.
That does not even pass the logic test. There would no longer be any fire detection if the cables burned first.
Re: Layout of Fire Detection Distribution System
Cable in confuit will melt/burn as fast, or faster as open air cabling. Hopefully, one of your detectors has triggered an alarm before this occurs. This is also why you use Class A wiring and short isolators.
If it's still a concern, you can use Circuit Integrity (CI) cable. There are several manufacturers, and most of it is similiar to MI cable. It will endure a fire longer than the building.
Cable in confuit will melt/burn as fast, or faster as open air cabling. Hopefully, one of your detectors has triggered an alarm before this occurs. This is also why you use Class A wiring and short isolators.
If it's still a concern, you can use Circuit Integrity (CI) cable. There are several manufacturers, and most of it is similiar to MI cable. It will endure a fire longer than the building.
Re: Layout of Fire Detection Distribution System
Actually, our lead fire protection Mechanical Engineer says that relating to initial fire impact to the cable, the cable will start burning later if in metal conduit. Using the example of a frying pan on a candle. The inside of the frying pan will get hotter later than the bottom of the frying pan.
I don't think the regs permit fire cable that is not mi or ci, otherwise metal cladded for protection. I have been told this and am now researching. It may be that I can not put cable in the rafters that is not encased in conduit if it is not even plenum rated.
Actually, our lead fire protection Mechanical Engineer says that relating to initial fire impact to the cable, the cable will start burning later if in metal conduit. Using the example of a frying pan on a candle. The inside of the frying pan will get hotter later than the bottom of the frying pan.
I don't think the regs permit fire cable that is not mi or ci, otherwise metal cladded for protection. I have been told this and am now researching. It may be that I can not put cable in the rafters that is not encased in conduit if it is not even plenum rated.
Re: Layout of Fire Detection Distribution System
Fire alarm cable must be encased in conduit or be metal clad per NFPA 72 as shown below. I believe the MI or CI cable you referenced will suffice. Putting in regular 18AWG cable for the purpose of reducing heat build up from conduit will is not permitted. It is theoried from our mechanical engineer that initial heat will build up slower in the conduit than in open air.
4.4.1.4.2 Mechanical Protection.
4.4.1.4.2.1 The dedicated branch circuit(s) and connections shall be mechanically protected.
Fire alarm cable must be encased in conduit or be metal clad per NFPA 72 as shown below. I believe the MI or CI cable you referenced will suffice. Putting in regular 18AWG cable for the purpose of reducing heat build up from conduit will is not permitted. It is theoried from our mechanical engineer that initial heat will build up slower in the conduit than in open air.
4.4.1.4.2 Mechanical Protection.
4.4.1.4.2.1 The dedicated branch circuit(s) and connections shall be mechanically protected.
peter d
Senior Member
- Location
- New England
Re: Layout of Fire Detection Distribution System
That rule only applies to the AC supply for the FA control panel. Unless you have local codes then you can "free air" the FA low voltage cable without conduit.
ron
Senior Member
- Location
- New York, 40.7514,-73.9925
Re: Layout of Fire Detection Distribution System
NEC Article 760 permits cable without raceway.
NEC Article 760 permits cable without raceway.
Re: Layout of Fire Detection Distribution System
Originally posted by eeee:
4.4.1.4.2 Mechanical Protection.
4.4.1.4.2.1 The dedicated branch circuit(s) and connections shall be mechanically protected.
--------------------------------------------------------------------------------
YOU STATE:
That rule only applies to the AC supply for the FA control panel. Unless you have local codes then you can "free air" the FA low voltage cable without conduit.
I HAVE THE FOLLOWING RESPONSE:
I read NEC 760. The old version of NFPA 72 (1993 that I have) did not seem to have any information concerning the dedicated branch circuits protection requirments specifically related to mechanical. I will confer with the mechanical engineer who has the new version electronically.
4.4.1.4.2.1 in NFPA 72 (new version per the mechanical engineer, the dedicated branch circuit(s) and connections shall be mechanically protected makes me think it is not the power cable that feeds the fire alarm panel (as you say) just by reading this sentence. I will validate with Mechanical engineer once he permits me to view the new version of the NFPA 72. I have a 1993 version.
I assume that the fire alarm cable must be NPLF such as ci or mi if it is to be left in open air per NEC 760.
I assume that installing regular 18AWG non fire rated control cable in open air is not permitted by NFPA 72 (I will validate with newer version of NFPA after I have an appointment to view it).
Installing regular 18AWG (non fire rated) cable in open air is what was suggested I do to save money and that it was thought this was permitted by the NFPA 72.
Originally posted by eeee:
4.4.1.4.2 Mechanical Protection.
4.4.1.4.2.1 The dedicated branch circuit(s) and connections shall be mechanically protected.
--------------------------------------------------------------------------------
YOU STATE:
That rule only applies to the AC supply for the FA control panel. Unless you have local codes then you can "free air" the FA low voltage cable without conduit.
I HAVE THE FOLLOWING RESPONSE:
I read NEC 760. The old version of NFPA 72 (1993 that I have) did not seem to have any information concerning the dedicated branch circuits protection requirments specifically related to mechanical. I will confer with the mechanical engineer who has the new version electronically.
4.4.1.4.2.1 in NFPA 72 (new version per the mechanical engineer, the dedicated branch circuit(s) and connections shall be mechanically protected makes me think it is not the power cable that feeds the fire alarm panel (as you say) just by reading this sentence. I will validate with Mechanical engineer once he permits me to view the new version of the NFPA 72. I have a 1993 version.
I assume that the fire alarm cable must be NPLF such as ci or mi if it is to be left in open air per NEC 760.
I assume that installing regular 18AWG non fire rated control cable in open air is not permitted by NFPA 72 (I will validate with newer version of NFPA after I have an appointment to view it).
Installing regular 18AWG (non fire rated) cable in open air is what was suggested I do to save money and that it was thought this was permitted by the NFPA 72.
Re: Layout of Fire Detection Distribution System
I got my answer from Monaco.
An addressable system requires non shielded twisted pair, plenum rated cable to be used without conduit.
A conventional system can use THHN non twisted pair in conduit unlike an addressable system that requires non shielded twisted pair in conduit.
The conventional system also requires plenum rated cable if not used in conduit.
I got my answer from Monaco.
An addressable system requires non shielded twisted pair, plenum rated cable to be used without conduit.
A conventional system can use THHN non twisted pair in conduit unlike an addressable system that requires non shielded twisted pair in conduit.
The conventional system also requires plenum rated cable if not used in conduit.
- Location
- Illinois
- Occupation
- retired electrician
Re: Layout of Fire Detection Distribution System
Plenum cable is only requied in "other spaces used for enviromental air".
Plenum cable is only requied in "other spaces used for enviromental air".
Ragin Cajun
Senior Member
- Location
- Upstate S.C.
Re: Layout of Fire Detection Distribution System
Was looking in past posts for information on another topic and stumbled on this one. Don's comment of:
"Again, in general, fire alarms protect people and sprinklers protect property" stood out. Well said!
don_resqcapt19 said:
Was looking in past posts for information on another topic and stumbled on this one. Don's comment of:
"Again, in general, fire alarms protect people and sprinklers protect property" stood out. Well said!
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