On the main alarm panel, there are two ground
indicator lamps to indicate the presence of a ground in
the alarm system. All shipboard alarm panels and
remote sensors are electrically isolated from the ships
ground. The only exception is the ground fault de-
tector, which is connected to ground for ground
If one or both lamps light, you should have the
alarm SWBD and its remote sensors serviced by an
electrician who has maintenance responsibility for
removing a very dangerous shock hazard. The
AUDIBLE silence control is a two-position switch
that permits silencing (VISUAL position) the audible
alarm on the main panel. The ALARM lamp on the
main panel is lighted when the AUDIBLE silence
control is placed in the VISUAL position, and the sys-
tem is in an alarm condition.
The lower half of the alarm panel holds the alarm
modules that are connected through the alarm panel to
the remote sensors. If additional remote sensors are
installed at a later date, a new alarm module is
plugged into the lower panel for each sensor installed.
Each alarm module includes a center-divided lighted
display. Either half can independently display a steady
red light, a flashing red light, or no light, depending
on the circuit logic.
The six possible combinations of alarm module
lights and the appropriate audible alarm are shown in
Figure 2-23.Alarm switchboard visual displays and audible outputs.