D
C
HSI #780-0867
FireSpy Tracker
Installation Manual
41
Table 3-6: Wire Lengths for Panel Network RS485
Units
18 AWG
16 AWG
14 AWG
12 AWG
Part number of cable referenced for ratings
Belden
9571
9572
9580
9582
Resistance rating of cable
ohm/kFT
6.3
4.1
2.5
1.6
Capacitance rating of cable
pF/ft
22
29
27
30
Max distance, resistance candidate (worst case)
ft
7937
12195
20000
31250
Max distance, resistance candidate (best case)
ft
15873
24390
40000
62500
Max distance, capacitance candidate
ft
6818
5172
5556
5000
Max distance, wavelength candidate
ft
4269
4269
4269
4269
Max distance (worst case load distribution)
ft
4269
4269
4269
4269
Max distance (best case load distribution)
ft
4269
4269
4269
4269
Many factors are involved with communication circuits. Special considerations may need to be made for any specific job,
especially if these distances are exceeded.
Resistance-based distance calculations were performed by using Eq. C-1
Wavelength candidates are based on 25% of the wavelength of the circuit’s operating frequency, 57600 baud
