The Genie 37909S Series III STB Extension Kit is a genuine OEM accessory designed to extend the reach of Genie Safe-T-Beam photoelectric safety sensors used on Series III garage door openers. It provides the components needed to lengthen the low-voltage wiring run for the self-diagnostic Safe-T-Beam system when the factory leads are not long enough due to routing changes, remodels, or repairs. Ideal as a replacement part or upgrade during opener service, this extension kit helps maintain dependable door-reversal protection by ensuring the infrared photo eyes can be mounted and aligned at the proper location along the garage door opening.
Compatible with Genie openers that use the Series III Safe-T-Beam system, the 37909S supports residential applications where reliable safety sensor operation is required to meet UL 325 requirements. Installation involves extending the existing low-voltage conductors from the opener’s STB terminals to the photo eyes, observing proper polarity and sensor LED indicators for alignment. For safety, disconnect power to the opener before working on wiring, mount sensors typically 5–6 inches above the floor on each side of the door, route cable away from moving parts, and avoid running sensor wires alongside high-voltage lines. Refer to the specific opener’s manual and the kit instructions for wiring diagrams and programming or reset steps after installation.