Protectowire PHSC series is manufactured using spring steel conductors, while the PLR series is manufactured with low resistance tri-metallic conductors that are engineered to enable longer detector zone lengths on other manufacturers’ control equipment.

The amount of Protectowire (PHSC or PLR series) that can be installed on another manufacturers’ control equipment is directly determined by the maximum loop resistance of the equipment’s initiating device circuit.

Protectowire’s PHSC digital linear heat detectors have an approximate resistance of 0.185 Ohms per foot (0.607 Ohm per Meter). Protectowire’s PLR digital linear heat detectors have an approximate resistance of 0.058 Ohms per foot (0.191 Ohm per Meter).

The PLR series detectors allow for approximately 3x longer lengths on the same initiating device circuit.