Temperatures and Temperature Variability in Lighting Fittings for Filament Lamps

Abstract

The paper investigates the effect of reduced lamp dimensions on fitting temperatures, and some aspects of temperature variability, specification and measurement. Data are given for the operating temperatures in a representative range of lighting fittings with 100 watt GLS lamps of many different designs, and with the proposed Standard Heat Test lamps. The smaller lamps and the Standard Heat Test lamps give higher fitting temperatures: some resulting design problems are discussed. Experiments to assess the inherent variability in fitting temperatures, not associated with measurement discrepancies, are described; the significance of the limited amount of testing economically possible is discussed, as it affects test specifications. It is shown that when drafting specifications, it is necessary to make allowance for the inherent variability, and a re-testing procedure is suggested. An appraisal is given of experience gained with early samples of the Standard Heat Test Lamp.