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FireLite SLC Wiring Manual — P/N 51309:R3 7/29/2019
Power Considerations Supervising 24 VDC Power
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. There-
fore, the relay needs to be installed at the end of the supervised 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 Class B or a Class A circuit.
The drawing below illustrates this concept.
An alternate method is shown below.
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
CMF-300
MMF-300
Power Supervision
Relay
(EOLR-1)
Supervised NAC
ELR 47K
24 VDC Power from
Control Panel or Power Supply
S
L
C
-
p
s
r
-
2
a
d
d
r
e
s
s
t
p
H
.
w
m
f
ELR 47K
Figure A.2 Alternate: 2-Address Method of Supervising a 24 VDC Circuit
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