A range of T-1 (3mm) Bi-pin filament indicators, specifically intended for illumination in confined spaces, e.g. meters, switches, etc.

Wire-Ended & Bi-Pin

Filament lamps will perform to specification and give optimum life when:,a) They are powered at the rated voltage from a stabilised 50Hz ac supply,b) Ambient temperature is in the range 20 to 25°C,c) No mechanical vibration is present.,Deviations from these criteria can have a significant effect on lamp life, particularly with low current filaments (<80mA). Operation from a dc supply at rated voltage can reduce specified life by up to 50%. The effect of variation from the rated operating voltage should be noted: 5% above will reduce lamp life by up to 50%. 5% below will significantly increase lamp life. Current consumption can vary by up to ±10% on stated values at rated supply voltage. Care therefore should be exercised when running a number of lamps in series. In such applications it is recommended that the rated voltage be reduced by 10% to prevent premature failure of individual lamps.