EOL Resistors

An end of line resistor sits at the far end of a supervised fire alarm circuit and lets the control panel tell the difference between a healthy circuit, an open and a short. The panel passes a small supervisory current through the wiring and through the EOL resistor. If a conductor breaks, the current stops and the panel reports a trouble; on an initiating device circuit, a short raises the current and the panel reports an alarm. Without the resistor the panel cannot supervise the wiring at all, which is why a missing or wrongly valued one is a routine finding on inspection.

The resistor value is set by the panel manufacturer, not chosen by the installer, so the right end of line resistor is the one specified for that panel and that circuit type. Initiating device circuits, notification appliance circuits and releasing circuits each have their own requirement.

We stock EOL resistors loose, on leads, in bulk packs, and as assemblies on plates, in modules and in end of line boxes, from Fire-Lite, Simplex, Notifier, Edwards, Kidde, Kidde Fenwal, Potter, Mircom, Hochiki, Secutron, Protectowire and STI. Need an obsolete value or assembly? Ask on our quote page.