Unfortunately the information relationship is a bit muddy between NFPA 70 and 72. Usually some building or life safety code tells you where detection is required and other aspects of the big picture, then 72 gives more application information of where and how to's, then 70 tells you about cable/wire, raceway, boxes, etc. The information in 70 is not only in 760 but in the multiple references to articles in Chapters 1-4. There is even a new smoke detector related requirement that shows up beginning in 2002, that is hiding in 645, if you frequent that part of the code.
Re: Article 760 Fire Alarm Systems and NFPA 72#91801 02/06/0510:00 PM02/06/0510:00 PM
Ventilation in the underfloor area is used for the information equipment room only. The ventilation system shall be so arranged, with approved smoke detection devices, that upon the detection of fire or products of combustion in the underfloor space the circulation of air will cease.
Commentary: This requirement has been revised for the 2002 Code. The underfloor area is required to be provided with smoke detection device(s). Upon detection of smoke, the circulation of air in the underfloor area must be interrupted. The most common method of interrupting air circulation is to open the circuit that supplies power to the air circulation fan.
In addition to causing cessation of air circulation in the underfloor area, the smoke detectors may provide other fire protection functions as part of a complete building fire alarm system.
Joe Tedesco, NEC Consultant
Re: Article 760 Fire Alarm Systems and NFPA 72#91802 02/06/0511:12 PM02/06/0511:12 PM
I find it interesting that the smoke detector only has to interrupt the air flow. It isn't required to initiate any audible or visual signals. Kinda drives home ther difference between a smoke detector and a smoke alarm.
Re: Article 760 Fire Alarm Systems and NFPA 72#91803 02/08/0503:10 PM02/08/0503:10 PM
Is it possible tp install smoke detectors without installing a FACP? In other words, can I use a smoke detector to control a relay and thus break a set of contacts and drop out the fan and stop the air circulation in the "Computer room"?
Re: Article 760 Fire Alarm Systems and NFPA 72#91805 02/08/0504:38 PM02/08/0504:38 PM
Thanks for the feedback, I was involved in a Basic Fire Alarm Class and most of the students were electricians, some journeymen one master and a few apprentices. They too did not use NFPA 72, and when I mentioned the NEC Article 760, 300.21, 22, and 23 and other rules as they're aware, their face's all dropped.
Am I missing something, or is our trade going downhill?
Joe Tedesco, NEC Consultant
Re: Article 760 Fire Alarm Systems and NFPA 72#91807 02/08/0506:28 PM02/08/0506:28 PM
I don't know if I would characterize it as going down hill, although they should be following the NEC sections you quoted.
In my mind the design of modern fire alarm systems is so complex at this point that it needs to be handled by specialists in that field.
The risk are to great and the issues can be complex.
Once you get into larger buildings with smoke evac, elevators, building automation systems, rooms in buildings with separate pre action systems, the list is endless you need someone who really knows their stuff.
The energy codes are forcing the lighting systems to shut down all the lighting when not in use so now we need a tie from the fire alarm to the lighting controls.
Elevators, you have primary and alternate floor recalls which has to be properly programed into the panel.
When we have banks of elevators the emergency generator may only be sized to run one at a time now recall must be coordinated with the specialized elevator power transfer switch.
I am happy to work of a detailed set of prints, I still have to know and follow the NEC and it still takes a craftsman to make it look good and operate correctly.
Bob Badger Construction & Maintenance Electrician Massachusetts
Re: Article 760 Fire Alarm Systems and NFPA 72#91808 02/08/0508:39 PM02/08/0508:39 PM
From a business perspective, an electrician should have a copy of NFPA 72, and be somewhat familiar with it in order to get extras! For some reason there might be 900 smoke detector on the project, and if I missed one on the Contract Drawing, that is picked up by the EC, the one extra detector always costs $2,000! I'm being funny , but there is lots on $$$ in change orders if you can pickup on missing stuff. Of course I'm glad that not to many folks know 72, so that when I screw up on a design, it doesn't get thrown in my face. That concept applies to many areas of NFPA 70 too!