Edwards Signaling eFSA250 User Manual
Page 232
Appendix B: Worksheets
220
E-FSA64 and E-FSA250 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 Ω/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 Ω
Lc = (Rmax / Rw) / 2
= (2.0 Ω / 0.002 Ω/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
Table 47: eFSA64 panel
Current 12 AWG
14 AWG
16 AWG
18 AWG
0.5 A
2,228 ft.
1,400 ft.
879 ft.
553 ft.
1.0 A
1,088 ft.
684 ft.
429 ft.
270 ft.
1.5 A
708 ft.
445 ft.
279 ft.
175 ft.
2.0 A
518 ft.
326 ft.
204 ft.
128 ft.
2.5 A
404 ft.
254 ft.
160 ft.
100 ft.
Table 48: eFSA250 panel
Current 12 AWG
14 AWG
16 AWG
18 AWG
0.5 A
2217 ft.
1394 ft.
875 ft.
550 ft.
1.0 A
1,077 ft.
677 ft.
425 ft.
267 ft.
1.5 A
697 ft.
438 ft.
275 ft.
173 ft.
2.0 A
507 ft.
319 ft.
200 ft.
126 ft.
2.5 A
393 ft.
247 ft.
155 ft.
97 ft.