Philips 327817 35-watt T15 SOX Low Pressure Sodium Bulb

Low pressure sodium technology occupies a narrow but important niche in the lighting spectrum: applications where maximum lumens-per-watt efficiency and long service life matter more than color quality. The Philips 327817 35-watt T15 SOX lamp is engineered for exactly these environments — roadways, tunnels, bridges, security perimeters, railway crossings, and airport boundary lighting where the goal is reliable, high-output visibility at the lowest possible operating cost. Its near-monochromatic 589nm output produces the characteristic yellow-orange cast of SOX lighting, which human eyes perceive with high contrast in low-ambient conditions, making it effective for perimeter and safety applications.

The lamp is built around a rough service arc tube support system that resists mechanical shock and vibration — a practical necessity for infrastructure installations subject to structural movement or nearby heavy machinery. Rated for up to 18,000 hours, it reduces maintenance intervals considerably compared to standard HID alternatives, which matters significantly in overhead or hard-to-access mounting positions. The D.C. Bayonet base is specific to SOX-compatible luminaires, and the base-up ±110° operating position requirement must be observed during fixture selection and installation to achieve rated performance. For facilities managers specifying long-life, low-operating-cost solutions for non-color-critical environments, the Philips SOX lamp remains a technically sound choice.