SilentKnight 5895XL 6A Intelligent Remote Power Supply - Manual (Page 17)

Before You Begin Installing
151142 2-7
2.7 Wiring Specifications
2.7.1 Length Limitations
This section contains information on calculating SBUS wire distances and the types of wiring
configurations (Class A and B).
2.7.2 Calculating Wiring distance for SBUS modules
The following instructions will guide you in determining the type of wire and the maximum
wiring distance that can be used with SBUS accessory modules.
To calculate the wire gauge that must be used to connect SBUS modules to the panel, it is
necessary to calculate the total worst case current draw for all modules on a single
4-conductor bus. The total worst case current draw is calculated by adding the individual
worst case currents for each module. The individual worst case values are shown in the table
below.
Note: Total worst case current draw on a single SBUS cannot exceed 1 amp. If a large number of accessory
modules are required, and the worst case current draw will exceed the 1 amp limit, then the current draw
must be distributed using 5895XL Power Expanders. Each 5895XL Power Expander provides an
additional SBUS, with an additional 1 amp of SBUS current. Wiring distance calculations are done
separately for each 5895XL, and separately for the panel itself.
After calculating the total worst case current draw, Table 2-5 specifies the maximum distance
the modules can be located from the panel on a single wire run. The table insures 6.0 volts of
line drop maximum. In general, the wire length is limited by resistance, but for heavier wire
gauges, capacitance is the limiting factor.
Model Number Worst Case Current Draw
5860 Fire Annunciator .100 amps
5824 Parallel/Serial Interface .040 amps
5880 LED IO Expander .250 amps
5865 LED Fire Annunciator .200 amps
5895XL Intelligent Power Supply .010 amps
5496 Intelligent Power Module .010 amps