FireLite SLC Wiring Manual — P/N 51309:P4 9/17/2014 69
Supervising 24 VDC Power Power Considerations
A.2 Supervising 24 VDC Power
Power used to supply 24 VDC detectors, notification appliances (using the CMF-300), and two
wire detectors (using the MMF-302) can be supervised with a power supervision relay. This relay,
energized by the 24 VDC power itself, is installed at the end of each respective power run and
wired in-line with the supervised circuit of any intelligent module.
24 VDC power must be provided from a UL-listed power supply for fire protection use.
When power is removed from the relay, the normally closed contacts open the supervised circuit,
generating a trouble condition. Therefore, the relay needs to be installed at the end of the super-
vised circuit, so it will not disrupt the operating capability of all the devices on that circuit. The
relay can be installed in-line with any leg (+ or –) of the supervised NAC circuit, either a Style B
(Class B) or a Style D (Class A) circuit.
The drawing below illustrates this concept.
S
L
C
-
p
s
r
t
p
H
.
c
d
r
24 VDC Power from
Control Panel or
Power Supply
Power Supervision
Relay
(EOLR-1)
Supervised NAC
ELR
47K
Last device on the SLC loop
Figure A.1 Supervised 24 VDC Circuit
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