NEC 760 Power for fire alarms

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petercz

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Dear gentleman, regarding NEC Standards 760.21 and 760.41, Could any one clarify exactly what "nonpower limited fire alarm circuit" (NPLFA)is? And what Power-limited fire alarm circuit (PLFA) is? In Muke's article regarding Significant Proposals for 2005 NEC, he put in parenthesis for each of the above a 120V. So are they both feeding from statndard 120V A.C.? Or what exact voltage value(s) each can have? I thought that non-power limited would be from standard A.C. power, and power-limited would be from low voltage, moustly D.C. power. The standard is badly verbalized and is unclear about this. The standard is also unclear as to When and/or Where each of these power sources must be used in feeding fire alarm systems?
Could you please clarify?
Thanks,
Peter
 
Re: NEC 760 Power for fire alarms

NPLFA circuits are just that, non-power limited. A PLFA circuit has power source limitations as indicated in Tables 12(A) & (B) in Chapter 9 of the NEC.
 
Re: NEC 760 Power for fire alarms

Hi Bryan,
I thank you for your answer.
in all this 760.21 and 760.41 codes of power supplies for fire alarms what I do not know is When or Where to apply each:
Do I specify the NPLFA (non power limited) supply to feed a FA system in a regular residential building for example, with a standard 120V A.C. supply? Can also PLFA supply be used there?
Or is it stated somewhere in the standard that the PLFA supply should be used only in Hazardous installations or other special locations?
What I am asking is When and/or Where do I specify each power supply and where is the Standard's requirement for same?
Or, in your view perhaps I should not mention any of these at all on my blue-prints, since the manufacturer of the FA system has to provide the whole system all correct?..
Also, on the Right side part of Table 12(A) of Capt. 9 you can see provision for up to 150V Non-limited but current limited to 1A.
Thanks again,
Peter
 
Re: NEC 760 Power for fire alarms

Most of the time that I've experienced the differences between NPLFA and PLFA, is control panel manufacturer specific.
Different manufacturers seem to have their own preferences depending on the type of power supply they installed.
 
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