HCA Series Installation Manual
Page 47 of 58
V2.15
5.4.4 How to Install the Disconnect Switch on the Releasing Circuit
NFPA requirements state that a releasing service fire alarm system shall be provided with a disconnect
switch to allow the system to be tested without actuating the fire suppression systems. This disconnect
switch shall be a physical switch. When the switch is operated the panel shall indicate a supervisory signal
at the control unit (NFPA 72 2010 Edition, 23.13.5). This section explains how to connect the disconnect
switch to the HCA.
You will need a Hochiki America SOM-R-DS Disconnect Switch for this application.
The disconnect switch is connected in-line with the releasing circuit (NAC 1). When the switch is operated,
it creates an open-circuit condition which prevents the release of the extinguishing agent. The switch is
also connected to Zone 5 on the panel. When the switch is operated to disable NAC 1, zone 5 will be
activated to indicate a supervisory signal at the panel.
EOL Device
ACTUATOR/
SOLENOID
NAC 1
ZONE 5
+
+
-
EO
L
Switch is shown in the Disconnected (Disabled) position.
+ -
ZONE5
N
A
C
1
-
+
EOL Device
0400-02590
+
+
-
DISABLE
EOL Resistor
0400-01820
SOM-R-DS
Figure 5.4
– Disconnect Switch for Releasing
