FireLite SLC Wiring Manual —
P/N 51309:R3
7/29/2019
15
Measuring Resistance & Length
Wiring Requirements
2.
Repeat this procedure for all remaining branches in the SLC.
Total Wire Length
The total wire length of all combined branches of one SLC cannot exceed the limits set forth in each system’s instruction manual. Deter-
mine the total length in each SLC by summing the wire lengths of all branches of one SLC.
In the following figure, the total length of the SLC is determined by adding the lengths of Branch A plus Branch B plus Branch C.
2.2.2 Four-Wire SLC Class A and Class X
Loop Resistance
The total DC resistance of the SLC pair cannot exceed 40 ohms. Measure DC resistance as detailed and shown below.
1.
Disconnect the SLC channel B (Out) and SLC channel A (Return) at the control panel.
2.
Short the two leads of SLC channel A (Return).
3.
Measure the resistance across the SLC channel B (Out) leads.
SL
C-m
e
a
s
1.wmf
SLC Out
Branch
Short Point
Figure 2.1 Measuring DC Resistance of a Two-Wire SLC
Branch A
Branch B
Branch C
S
L
C-me
as2
.wmf
SLC Terminal
Block
Figure 2.2 Measuring the Total Wire Length - Two-Wire SLC
SL
C
-m
e
a
s
3.
wm
f
SLC Out
SLC Return
Short Point
Figure 2.3 Measuring DC Resistance of a Four-Wire SLC