How to replace a broken Passive Infra-red (PIR) Detectors


How to replace a broken Passive Infra-red (PIR) Detectors


Passive infra-red (PIR) detectors and Dual technology (PIR/Microwave) detectors are interchangeable. For example you may wish to swap a standard PIR for a pet friendly version or for a dual technology type. All PIRs and dual tech. detectors have six connections thus:
2 cores for 12v DC +/- power from the control panel,
2 cores for the alarm circuit,
2 cores from the tamper circuit.

Step One

If the system has been fitted correctly, then removing the cover from the PIR or the Control Panel will produce an alarm - caused by the tamper circuit. This alarm can be silenced by entering the user code. If you are in possession of the engineer code then you can enter engineer mode and thus suppress any tamper activations. Because the detector is powered via a fused output from the control panel, it is important not to short the power supply. The easiest way to prevent shorting is to remove the auxiliary power supply fuse at the control panel. Failing that, both power supply wires should be insulated as they are removed from the PIR terminal block.WARNING: Remove the mains power supply to the Control Panel BEFORE opening the Control Panel.

Step Two

If applicable, remove the control panel cover and silence the alarm by entering the user code. Identify the auxiliary power supply fuse and remove it. At the PIR; remove the cover from the PIR - silence the alarm if necessary.

Step Three

Identify and record the cable core colours - the alarm pair and the tamper pair are not polarity dependent. NOTE: If the PIR has been daisy-chained with another detector locally, then there may be one or more connecting blocks in the detector. The integrity of the connections must be maintained. It is important to identify the power supply connections before dismantling any joints and insulate them as below.

Step Four

If the fuse has not been removed from the control panel, remove one of the power supply cores and insulate it - do NOT allow it to contact any part of the PIR PCB or the terminal block. Repeat the above for the other power supply cable.

Step Five

Remove the remaining cables from the terminal block. Carefully pull the cable out of the PIR. NOTE: It may be necessary to remove the PCB from the PIR housing. Remove the PIR from its mounting.

Step Six

Fitting the New PIR - Before permanently fixing the new PIR in position, ensure that the existing cable will reach the terminal block in the new PIR. Extend the cable using a suitable junction box as required.Remove the PCB from the PIR housing.

Step Seven

Identify the mounting holes to be used for mounting the PIR and remove the required knockouts. Identify the cable mounting hole(s) - if the PIR is daisychained to another detector then there may be two cables entering the PIR. Remove the knockouts for the cable entry point(s). NOTE: Do not make the cable entry larger than required - the cable should be a snug fit in the entry hole in order to stop insect/dust ingress.

Step Eight

If required, drill and plug the mounting holes. Feed the cable through the PIR casing and secure the cable as required. Fix the PIR casing to the wall/ceiling. Connect the cable cores to the correct terminals on the terminal block.

Step Nine

Refit the PCB and adjust its position for the correct mounting height. Refit the cover. Replace the fuse in the control panel if applicable. Refit the control panel cover, restore the mains supply and reset the control panel.

Step Ten

The new PIR should now be functional. If the walk test LED has been left enabled it will respond to walk testing. NOTE: PIRs can take a couple of minutes to warm-up before they are fully functional.


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