Philips 368811 C400S51/ALTO

Philips 368811 C400S51/ALTO — 400W High Pressure Sodium Lamp, E39 Mogul Base

The Philips 368811 C400S51/ALTO is a 400-watt Ceramalux ALTO High Pressure Sodium (HPS) lamp from Philips Lighting, designed for outdoor area lighting, street lighting, and industrial high-bay applications. With an E39 Mogul Screw base, ED18 bulb shape, ANSI code S51, 100V arc tube operating voltage, and universal burn position, this lamp delivers 50,000 initial lumens and a 24,000-hour rated life. The ALTO designation indicates reduced mercury content. Verify wattage, voltage, ANSI code, base type, and ballast compatibility before ordering — HPS lamps require an HPS-rated ballast and ignitor.

Technical Specifications

Product Overview

The Philips 368811 C400S51/ALTO is a professional-grade HPS replacement lamp engineered for high-output outdoor and industrial lighting. At 400 watts, it delivers 50,000 initial lumens (45,000 mean lumens) — strong efficacy for large-area street, parking, and perimeter lighting as well as warehouse and industrial high-bay fixtures. The warm amber 2100K output is characteristic of High Pressure Sodium technology and is well suited for applications where visibility and energy efficiency take priority over color accuracy.

The ED18 bulb shape and E39 Mogul Screw base make this a direct replacement in fixtures previously housing a standard 400W HPS lamp with ANSI code S51. Arc tube operating voltage is 100V — confirm your ballast is rated for this voltage before ordering. Universal burn position allows installation in any orientation. Maximum overall length is 9.75". The ALTO designation indicates this lamp contains reduced mercury content compared to standard HPS lamps.

Not recommended for: retail displays, color-critical inspection environments, sports venues, or any application requiring CRI above ~20.

Compatible Applications

• Outdoor area and street lighting — Roadways, parking lots, municipal streetlights, and perimeter security lighting.
• Industrial and commercial high-bay — Warehouses, manufacturing facilities, and large indoor/outdoor commercial fixtures.
• Retrofit and maintenance replacement — Direct replacement for existing 400W HPS lamps with E39 base and S51 ANSI code. Verify ballast compatibility and arc tube voltage before ordering.

Before Ordering — Verify

• ANSI / Lamp Code: Confirm the existing lamp or equipment manual matches S51.
• Wattage: Confirm the fixture is rated for 400W.
• Arc Tube Voltage: Confirm the ballast is rated for 100V lamp operation.
• Base Type: Confirm the socket matches E39 Mogul Screw.
• Ballast Compatibility: This lamp requires an HPS-rated ballast and ignitor. It will not operate on a Metal Halide or Mercury Vapor ballast.
• Burn Position: Fixture supports Universal operation — no restriction.
• Physical Fit: Confirm ED18 bulb shape, 9.75" MOL, and fixture clearance against the existing lamp or fixture manual.

Safety and Handling Guidelines

• Correct Ballast Required: Use only with an HPS-compatible ballast and ignitor rated for this lamp. Using an incompatible ballast can result in lamp failure or fixture damage.
• High-Pressure Arc Tube: HPS lamps operate under high internal pressure. Always use appropriate eye protection when handling or replacing lamps. Allow lamps to cool fully before removal.
• Warm-Up / Restrike Time: HID lamps require a warm-up period to reach full output. After a power interruption, allow the lamp to cool before restarting — a hot restrike attempt can damage the lamp or ballast.
• Approved Fixtures Only: Install only in fixtures rated for the listed lamp type, wattage, voltage, and operating position.
• Mercury Content: Contains mercury (reduced content — ALTO). Do not dispose of in regular trash. Recycle through an approved lamp recycling program in accordance with federal, state, and local regulations.

Compliance

• ALTO designation indicates reduced mercury content per Philips ALTO series standards.
• Contains mercury — subject to applicable lamp recycling and disposal regulations. California, Washington, and other states may have mandatory take-back or handling fee requirements.
• Verify RoHS compliance status, UL listing, Title 20, and Prop 65 requirements with the Philips manufacturer specification sheet prior to use in regulated installations.

Ordering Information

• Brand: Philips Lighting
• Philips Order Code: 368811 (36881-1)
• SKU: PHLB36881
• UPC / EAN: 046677368814
• ANSI Code: S51
• Wattage / CCT: 400W / 2100K Warm Amber
• Base: E39 Mogul Screw
• Packaging: Sold individually.
• Case quantities and bulk pricing: Contact ADL Supply for volume orders.

For wholesale pricing, bulk availability, or help confirming the correct replacement lamp, contact ADL Supply at 1-800-235-3489.