NC941/SS
STAINLESS STEEL SINGLE ZONE CALL CONTROLLER c/w PSU
THIS EQUIPMENT MUST ONLY BE INSTALLED AND MAINTAINED BY A SUITABLY SKILLED OR TECHNICALLY
COMPETENT PERSON. THIS IS A PIECE OF CLASS 1 EQUIPMENT AND MUST BE EARTHED.
GENERAL
The NC941/SS is a stainless steel single zone call controller with a built-in
mains to regulated DC power supply providing 250mA at 13.5V. An on-board
buzzer, reset button and LED indicator are provided, making it ideal for all
types of single zone call communication applications including disabled persons
toilet alarms. The NC941/SS is compatible with all 800 Series call points,
ceiling pulls and remote sounders. A remote battery back-up kit (part no.
NC941B) can be connected to the NC941/SS to ensure it remains operational
for a limited amount of time in the event of Mains failure.
Call
OPERATION
The green 'ON' indicator indicates that the NC941/SS is powered up.
When a standard call is triggered at any device connected to the NC941/SS
overleaf)
Once the nature of the call has been investigated, it can be cancelled by pressing the 'RESET' button on the front of
the NC941/SS. Standard calls can also be cancelled at the originating device itself (if it has a reset facility) or via a
remote reset point
disabled by disconnecting the reset button (as described in Figure 1 overleaf).
For call points with emergency trigger option:
If an emergency call is triggered, the NC941/SS's buzzer will pulse and it's red 'CALLING' LED will flash. Emergency
calls override standard calls and can only be reset at the device from which they were generated.
The front of the NC941/SS may feel slightly warm. This is normal and does not affect the operation of the unit.
, the buzzer will generate a constant tone and the red 'CALLING' LED will illuminate.
(see wiring configuration diagram overleaf)
. If required, the NC941/SS's 'RESET' facility can be
(see wiring configuration diagram
ON
CALLING
RESET
INSTALLATION
Location
The NC941/SS must be sited internally 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 (please note, if required, overdoor lights and remote sounders can be
connected to the NC941/SS to increase call indication levels). Any likelihood of tampering or vandalism should also
be taken into account.
First Fix : Back Boxes
The NC941/SS must be fitted to a back box (minimum depth 40mm) that is securely fixed to a wall. The back box, in
conjunction with the front plate, comprises a fire compartment and therefore must be made of a flame retardant material.
For flush mounting, we suggest using an extra deep 47mm double gang steel flush back box such as Appleby's SB628
or MK's 878 ZIC. For surface mounting, we suggest the MK K2212 ALM or 2212 ALM Aluminium coloured. If a plastic
dry lining box is required, use the Marshall-Tufflex MDLB30.
the onus is on the installer to check the suitability of any back box prior to first fix. Generally speaking, steel back
boxes with side mounted earth connections will not be suitable.
Any apertures must be sealed off so as not to compromise the integrity of the fire compartment. i.e any knockouts
removed must be sealed with a flame retardant gland. Any dust created during the fixing process must be kept out
of the electrical and electronic systems, and care must be taken not to damage any wiring or components.
First Fix : Mains Wiring
The NC941/SS is a piece of Class 1 equipment and, as such, any metal parts used during installation (i.e.
metal back box) MUST be earthed.
All mains wiring should be provided in accordance with the current edition of the IEE Wiring Regs, 16th Ed. (BS 7671
1993) or in accordance with the relevant national wiring rules.
All of the above suggestions are given in good faith but
800 SERIES
call system
Approved Document No. DNU0941099 Rev 1
continued overleaf >>>
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The general requirement for the Mains supply to the NC941/SS is fixed wiring, using three core cables of not less than
1
1
1
1
1
1
1
1
1
1
1
1
0.75mm
2
. This should be fed from an isolating switched fused spur, fused at 3A, which is marked appropriately and is
secure from unauthorised operation. (As an alternative to a switched fused spur, any double pole isolating device with
an air gap greater than 3mm when isolated may be used).
Live and neutral should be connected to the terminals marked L and N respectively at the connector block labelled CONN1.
The incoming mains earth should be connected directly to the NC941/SS's earth post marked (see Figure 1 below).
If a metal back box is used, an auxiliary earth connection must be made between this earth post and the earth bonding
point on the metal back box.
All external wiring brought into the unit must be adequately insulated with PVC or Neoprene.
Figure 1 : NC941/SS PCB LAYOUT
To earth bonding
point on metal
back box (if fitted)
INCOMING
MAINS
L
N
CONN1
The terminal block CONN3 is provided for the connection of an optional NC941B remote battery back-up kit. Do not
connect any other type of battery back-up facility to this unit. (See NC941B instructions for battery connection details).
First Fix : Low Voltage Wiring
All low voltage wiring coming into the NC941/SS must be carefully planned before starting the job. An example wiring
configuration diagram showing how ancillary devices can be connected to the NC941 is shown in the Typical Wiring
Configurations diagram below. Always segregate low voltage wiring from mains wiring.
-VE The common 0v terminal for all devices.
+VE +12V nominal supply for powering emergency call points, overdoor lights, etc.
SIGNAL The trigger line which activates the NC941.
OUTPUT Goes to +12V when the buzzer sounds (20mA max o/p).
Before screwing the plate to the wall, take care not to trap any wires.
Important: In the event of a short circuit (not on the mains), a low voltage fuse (F1) will blow to protect the unit
from damage. When replacing this fuse, only use a 400mA T fuse, 20 x 5mm to IEC (EN60127 part 2). The NC941 is
also protected by a thermal fuse in the mains winding of the transformer. This fuse will blow in the event of a serious
malfunction or misuse of the unit. If this happens, the unit must be returned to the manufacturer for repair as this
part is non-accessible and therefore non-replaceable by service personnel.
CONN3
Batt.+
to remote
battery
if fitted
Batt.–
234567890
234567890
234567890
234567890
234567890
234567890
234567890
234567890
234567890
234567890
234567890
234567890
To disable the NC941/SS's
reset button, disconnect the
wire from this screw terminal
and ensure the end of the
wire is insulated to protect
F1
-VE
+VE
SIGNAL
OUTPUT
CONN2
against inadvertent short
circuits
NC941/SS SPECIFICATIONS
Supply In: 230 VAC ± 10% @ 50/60 Hz; Max current: 36 mA; Supply Out: 13-13.8 VDC; 250mA @ 240VAC;
Physical Sizes: 156mm W x 94mm H x 37mm D; Protrusion depth into back box: 40mm; Weight: 460kg.
TYPICAL WIRING CONFIGURATIONS
Other possible configurations
-VE +VE
REMOTE
SOUNDER
SIGNAL
EMERGENCY
-VE +VE
CALL POINT
-VE
+VEI
SWITCHABLE
SOUNDER
Parts supplied in NC950/SS Economy Kit
SIGNAL
OUTPUT
SINGLE ZONE
CALL CONTROLLER
c/w PSU
BATT
BATT
+
to optional remote NC941B
remote battery back-up kit.
800 SERIES
call system
-VE
–
Parts supplied in NC951/SS Standard Kit
+VE
-VE SIGNAL
CEILING
PULL
UNIT
Approved Document No. DNU0941099 Rev 1
1
1
-VE +VE
OVERDOOR
LIGHT c/w
SOUNDER
SIGNAL -VE
RESET
POINT
contact your distributor for details on these and other compatible products
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