Zone Alarms

Zone Troubles

Missing ELR on the zone terminals

Zone Alarms

I just installed a control panel. Why is one of the zones in alarm? Besides the obvious activated initiating device, a number of conditions can cause a control panel to go into alarm:

• The initiating circuit wires are switched at one or more of the devices on the circuit.
• If the wiring was pulled through conduit, it may be stripped of its insulation - shorting the wires together and causing an alarm condition on that circuit. This can also cause a Ground Fault condition as the bare wiring comes into contact with the grounded conduit.
• Too many conventional smoke detectors installed on the circuit. Each detector adds a small amount of supervisory current to the circuit. As this current increases with each device, it approaches the alarm current threshold. When too many detectors are installed, the supervisory current puts the zone into alarm. Reference the Device Compatibility Document for details on the number of specific-model detectors that can be installed on a specific control panel Initiating Device Circuit.
• The wrong value of End-of-Line Resistor (ELR) is installed on the circuit. Refer top the control panel documentation for the correct value.
• An initiating device has malfunctioned, causing a short on the circuit.
• Electrical "noise", such as produced by hand-held radios and other communications equipment, may be inducing a voltage spike that latches the zone into alarm.

To troubleshoot a circuit:

1. Remove the circuit wires from the control panel.
2. Return the End-of-Line Resistor to the terminal block. If this clears the alarm, the problem exists out on the circuit.
3. Inspect the circuit beginning with the first installed device.

To determine if the alarm (on a new or existing panel) is a field wiring/device problem or a possible panel problem:

1. Remove the field wiring and place the proper End of Line Resistor (ELR) value on the zone terminals of the panel.
2. Reset the panel.
   
   If the alarm condition clears, the problem lies in the field wiring/devices. If the problem stays with zone, power down completely, remove ALL the field wiring, and place ELRs on all the zones. If the problem remains, repair or replace the control panel.

Zone Troubles

Any open-circuit (or near-open circuit) condition causes an Initiating Device Circuit to register a trouble condition. This can be due to a wire break, a missing or wrong-value End-of-Line Resistor, or too many broken strands on stranded wire.

To determine if the alarm (on a new or existing panel) is a field wiring/device problem or a possible panel problem:

1. Remove the field wiring and place the proper End of Line Resistor (ELR) value on the zone terminals of the panel.
2. Reset the panel.

If the alarm condition clears, the problem lies in the field wiring/devices. If the problem stays with zone, power down completely, remove ALL the field wiring, and place ELRs on all the zones. If the problem remains, repair or replace the control panel.

Missing ELR on the zone terminals

If you have a panel zone that is not in alarm or trouble - swap the field wiring of the normal zone with the abnormal zone in trouble or alarm.

• If the problem moves to the normal zone, the problem exists somewhere on the circuit's field wiring.
• If the problem remains with the abnormal zone, the control panel itself may be at fault.