What Do The Resistors Do On A VISTA P System?

Resistors add an extra degree of security to the zone. Each Honeywell Vista series control panel comes with a set of resistors that are included in the hardware pack. One resistor is included for each zone on the panel.

Vista series control panels are designed to look for a specific resistance on zones and a resistor creates a resistance in the flow and reduces the current of electrical flow.

The Vista P control panel uses voltage to determine the status of the zone. If a voltage meter was connected to an unused zone with no resistor, it would read somewhere close to 12 volts. 12 Volts would mean there's an open circuit between zone positive and ground and the zone would show fault on the keypad. The Vista P control panel, uses 2000 ohm resistors on hardwire zones. With a 2K resistor on a Vista P control panel’s hardwire zone and a voltage meter was then connected, the voltage meter would read about 5 volts at its terminals. 5 Volts would mean the circuit is closed and the zone is clear.

Installing a resistor at the farthest device on the zone is known as EOL (end of line). Doing this creates a supervised circuit that can no longer be disabled by simply shorting it's wire somewhere along the wire run between the control panel and detection device.

This circuit will have a continuous path through the closed contact and the alarm panel will be able to see the 2000 ohm resistor. The zone will show normal on the keypad.

If the zone is a fire zone, the resistor should be placed in a parallel arrangement with the loop wires. If a device such as a smoke detector is triggered, the panel will detect a short circuit condition.