Many authorities insist that a call system’s reset function is carried out at ‘point of source’
(i.e. in the room in which the call was made). This is to ensure that the person who raised
the alarm is visited. As such, the default setting for Link PLK1 is link not fitted/no effect.
ENGINEER SELECTABLE FUNCTIONS
Figure 2 : Rear view of the NC942/NC942B Call Controller
(a) Reset the system
In this position, pressing the controller’s RESET button when a standard call is
active will return the controller to its normal state.
(b) Mute the system
In this position, pressing the controller’s RESET button when a standard call is
active will mute the controller’s on-board sounder.
(c) Have no effect
In this position (no link fitted), pressing the controller’s RESET button when a
standard call is active will have no effect.
Volume control
(Potentiometer VR1)
Potentiometer VR1 can be used to adjust the level of the call controller’s on-board
sounder. Turning the control clockwise with a terminal screwdriver will increase
the volume, turning it anti-clockwise will decrease it.
On-board volt-free relay operation
(RLY1)
The call controller includes an on-board volt-free relay with normally open (NO),
normally closed (NC) and common (C) contacts. The relay contacts are rated at
30Vd.c. @ 1A and can be used to switch optional externally powered devices such
as sounders, strobes or the extra low voltage coils of mains controlling relays.
When no calls are on the system, the normally closed contact is made. When an alarm signal
is present, the relay switches and the normally open contact is made. Muting the system will
have no effect on the relay’s operation.
Reset button operation
(Link PLK1)
Link PLK1 allows the call controller’s on-board RESET button to be set up to:-
L
N
PLK1
Reset Mute
Volume
+
V
E
SIGNAL
-V
E
NO
C
N
C
RECHARGEABLE
BATTERY BACKUP
SUPPLY COVER
NC942B
MODEL ONLY
Fit to
Enable
battery
PLK2
CONN3
CONN2
VR1
RLY1
Reset
!!!!!!!!!!!!!!!
Mute
Reset
!!!!!!!!!!!!!!!
Mute
Reset
!!!!!!!!!!!!!!!
Mute
(no
!
link
!
fitted)
!
Volume
Approved Document No: DNU0942000 Rev 1 • Page 3 of 4
Approved Document No: DNU0942000 Rev 1 • Page 2 of 4
INSTALLATION
ALWAYS ENSURE THE MAINS SUPPLY IS ISOLATED BEFORE MAKING ANY CONNECTIONS.
The call controller should be sited internally on a standard UK double gang back box (minimum
depth 25mm) in an area where it is readily accessible by the person(s) designated to use it. The
area should be clean and dry and the ambient light and sound levels should allow the status of
the indicators and internal sounder to be seen and heard. Any likelihood of tampering or
vandalism should also be taken into account.
Figure 1 : Example NC942/NC942B Call Controller Wiring
Mains wiring
The general requirement for the mains supply to the call controller is fixed wiring, using three
core cable of not less than 1mm
2
. This should be fed from an isolating switched fused spur,
fused at 3A, which is marked appropriately and secure from unauthorised operation.
Live and neutral should be connected to the controller’s L and N terminals
respectively. If a plastic back box is used, make the earth connection to the
terminal marked at connector block CONN2. If a metal back box is used,
the earth connection must be made to back box’s earth bonding point.
All external wiring brought into the unit must be adequately insulated with
PVC or Neoprene.
All mains wiring should be provided in accordance with the current edition of the IEE Wiring
Regs (BS 7671) or in accordance with the relevant national wiring rules.
Extra low voltage (ELV) wiring
Four core stranded burglar alarm cable is ideal for the extra low voltage wiring on most installations.
All extra low voltage wiring must be carefully planned before starting the job. Always segregate
extra low voltage wiring from the mains wiring.
In the event of a short circuit on the extra low voltage wiring, an internal self-resetting fuse will
temporarily isolate the system until the fault is cleared. The Call Controller is also protected by a
non-serviceable thermal fuse in its transformer winding which will blow if there is a serious
malfunction. If this happens, return the controller for repair.
L
N
CONN2
A maximum of five 800 Series devices (ceiling pulls, call points, overdoor lights,
reset points, etc.), can typically be connected to the call controller. Always refer
to the installation instructions supplied with each device before installation
NO
C
NC
CONN3
-Ve SIG +Ve
1 -Ve +Ve
Spr Sig -Ve
Sig -Ve +Ve
Sig -Ve
+Ve
NC C NO
NEGATIVE
SIGNAL
POSITIVE
RESET
Call
CALLING
F
U
S
E
ON
Call
RESET
Call
ALERT
RESET
CALL
NC942/NC942B
Call Controller
NC806CS Overdoor
Light c/w Sounder
NC807C
Ceiling Pull
NC809DBB Reset
Point c/w Sounder
NC802DEB-1/2
Emergency Call Point
1mm
2
T&E
Three cores of four
core stranded burglar
alarm cable
3A Switch
Fused Spur
