Appendix B: Worksheets
214 EST iO64 and iO500 Technical Reference Manual
Example: You’re using regulated notification appliances. Assume
that the maximum operating current for each appliance is 100 mA
for FWR power, and that 20 appliances will be placed on the NAC.
The cable is 12 AWG wire, and the manufacturer specifies a wire
resistance factor of 0.002 /ft.
Itot = ΣIa
= 20 × 0.1 A
= 2 A
Vm = Vr (Itot × K)
= 20.4 V (2 A × 0.20 V/A)
= 20.4 V 0.40 V
= 20.0 V
Vd = Vm Va
= 20.0 V 16.0 V
= 4.0 V
Rmax = Vd / Itot
= 4.0 V / 2.0 A
= 2.0
Lc = (Rmax / Rw) / 2
= (2.0 / 0.002 /ft.) / 2
= (1,000.0 ft.) / 2
= 500.0 ft.
So the maximum wire run for this NAC would be 500 ft. (rounding
down for safety).
NAC maximum wire run quick reference tables
64 point panel
Current 12 AWG 14 AWG 16 AWG 18 AWG
0.5 A 4,455 ft. 2,801 ft. 1,758 ft. 1,106 ft.
1.0 A 2,176 ft. 1,368 ft. 858 ft. 540 ft.
1.5 A 1,416 ft. 890 ft. 558 ft. 351 ft.
2.0 A 1,036 ft. 651 ft. 408 ft. 257 ft.
2.5 A 808 ft. 508 ft. 319 ft. 200 ft.
250/500 point panel
Current 12 AWG 14 AWG 16 AWG 18 AWG
0.5 A 4,435 ft. 2,788 ft. 1,750 ft. 1,101 ft.
1.0 A 2,155 ft. 1,355 ft. 850 ft. 535 ft.
1.5 A 1,395 ft. 877 ft. 550 ft. 346 ft.
2.0 A 1,015 ft. 638 ft. 400 ft. 252 ft.
2.5 A 787 ft. 495 ft. 310 ft. 195 ft.
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