Nexus 21 A1557 An Overview of the Commissioning Procedure, Pre-Commissioning Wiring Check

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.

6.2An 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.

6.3Pre-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.

6.3.1The 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.

6.3.2Ensure 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.

6.3.3Ensure that resistance of all cables to earth and between cores is more than 1MΩ. Check the following:

(i)Positive to earth resistance is greater than 1MΩ

(ii)Negative to earth resistance is greater than 1MΩ

(iii)Positive to negative resistance is greater than 1MΩ

(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.

6.3.4Power 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.

6.4Commissioning Procedure

6.4.1Alarm Circuits

After completion of the pre-commissioning wiring check, this procedure should be followed:

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