What are the NAC circuit specifications for the NFS2-640, and when do I need an external NAC booster panel?

NotifierNFS2-640Mar 23, 2026
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The NFS2-640 features four onboard Notification Appliance Circuits (NACs) rated at 1.5 A each (Page 2) [1].

These 24 VDC circuits are supervised and power-limited, supporting both Class B (Style Y) and Class A (Style Z) configurations using a 2.2K ohm end-of-line resistor (Page 37) [1].

SpecificationRating
Number of Circuits4
Current per Circuit1.5 A
Total Shared Alarm Power6.0 A
Voltage24 VDC
EOL Resistor2.2K ohm, 1/2 watt

An external NAC booster panel is required if the total current demand of all notification appliances exceeds the 6.0 A shared power limit, or if any single circuit's load exceeds 1.5 A (Page 37) [1].

Note that the 6.0 A limit is shared between the four NACs and all other internal panel circuits and modules during an alarm condition (Page 2) [1].

AI-generated — verify against your panel's documentation and applicable codes (NFPA 72, local AHJ).

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