HPL 375

Overview

"HPL 375" refers not to a fixture, but to a light source: the 375-watt variant of the HPL lamp family ("High Performance Lamp"). HPL lamps are compact tungsten-halogen lamps with a special base featuring an integrated heat sink. The HPL design originates from ETC (developed by Ushio in 1994 to ETC design specifications) and is tailored for the ETC Source Four luminaire series (ellipsoidal/profile spotlights, PAR, and PARNel). The lamp is currently manufactured by several companies (including Osram/Sylvania, Ushio, Eiko, GE). The HPL base ensures a precise, reproducible filament position within the reflector system, which is why HPL lamps are used almost exclusively in Source Four-compatible fixtures.

Within the HPL family, the 375W version is the lowest wattage option; larger siblings include the common 575W and 750W lamps, as well as a 550W variant. The 375W version is chosen when less light output, lower heat generation, or reduced power consumption are desired. In standard catalogs (e.g., Osram/Sylvania), HPL 375 is listed for a mains voltage of 115V, making it primarily common in the North American market (115/120V mains).

Technical Data

Manufacturer specifications (Osram/Sylvania HPL Ultra Plus, UCF). There is a standard and a long-life "X" variant, which differ primarily in their average lifespan:

• Base: G9.5 (bi-pin) with a metal heat sink base, compatible with all generations of ETC Source Four fixtures.
• Technology: Tungsten-halogen; the Ultra Plus series utilizes the UCF ("Ultra Compact Filament") design for high luminous efficacy and a seamless construction to reduce filament shadows.
• Color Temperature: Approximately 3250K for the standard lamp (HPL 375/115); the long-life "X"/Long-Life versions are slightly lower at around 3050K. Refer to the respective data sheets for exact values from each manufacturer.

Set Usage

HPL 375 is used where the full output of a 575W or 750W Source Four is not required: in smaller setups, for softer accents, to limit heat load near performers or heat-sensitive materials, or to conserve dimmable circuit capacity. When changing lamps, never touch the bulb with bare fingers (grease residue shortens lifespan) and always use the variant appropriate for the mains voltage, as the voltage specification (115V) directly determines light output, color temperature, and lifespan.

The long-life "X" variant (1,000 h instead of 300 h) is suitable for installations and continuous operation where frequent lamp changes would be uneconomical; in return, it typically provides slightly lower luminous efficacy or color temperature (around 3050K) than the standard lamp.