Nexus 21 A1557 - Manual (Page 21)

Document Ref: Nex8inst.doc/Rev0 09.07.00 Page 21 of 30 Originator MC Checked by AC__
It is recommended that the electrical installer is made available until basic wiring continuity is
proven. A minimum of two persons (e.g. engineer and mate) is recommended for efficient
commissioning.
6.2
An Overview of the Commissioning Procedure
The approach to be used when commissioning a fire alarm system is to check each circuit and
function in turn to ensure correct operation of the entire system. In this way any faults may be
located quickly and accurately. The general procedures are as follows:
Alarm circuits should be checked first. The correct operation of each sounder should be
checked for correct audibility as specified in BS5839 part 1, using the “Test Alarms” facility.
Detection loops should be commissioned next. The purpose is to establish the correct
functioning of each device and checking for correct indication at the control panel. Any
auxiliary circuits may then be tested.
WARNING: Before testing, the engineer must be aware both of the operation of all devices
fitted to the auxiliary circuits and of the consequences of their operation.
6.3 Pre-Commissioning Wiring Check
NOTE: This pre-commissioning wiring check procedure should be followed to test all wiring
prior to specific commissioning of any detection, alarm and auxiliary circuits.
6.3.1 The following assumes that the control panel has been installed in accordance with the
installation procedure and is powered with only the “Power On” LED illuminated. Do
not connect field wiring at this stage.
6.3.2 Ensure that there are no devices connected to the loop and alarm circuits but the cables
are linked through at the device locations to achieve a continuous circuit.
6.3.3 Ensure that resistance of all cables to earth and between cores is more than 1M
Ω.
Check the following:
(i) Positive to earth resistance is greater than 1M Ω
(ii) Negative to earth resistance is greater than 1M Ω
(iii) Positive to negative resistance is greater than 1M Ω
(iv) Place a short circuit across the ends of the loop and alarm circuits. Measure the
resistance across the positive and negative cables of each of the circuits and ensure
that the value does not exceed the value calculated on the Loop Calculator
Spreadsheet. Remember to remove the short circuits after the tests.
Correct polarity throughout all circuits must be maintained. Rectify any faults.
6.3.4 Power down panel. All bells, detector heads and call points should now be connected
and alarm circuit end-of-line resistors fitted. Use the spare end-of-line resistors
supplied and leave the EOL resistors in the panel terminals at this stage. Be very
careful to maintain correct polarity at each device.
6.4
Commissioning Procedure
6.4.1 Alarm Circuits
After completion of the pre-commissioning wiring check, this procedure should be followed: