| abstract |
A light fitting 10 is powered from live L and neutral N mains supply lines including an override switch 32. The fitting comprises an array of LEDs 34, the output of which can be varied by a control circuit 36 including a timer 40, an occupancy sensor e.g. PIR 38, a photometer 42 monitoring ambient light level, and a trimpot potentiometer 44. The light fitting is turned on to maximum output only when a person is detected in the space to be illuminated and the ambient light level is below that. If no person is detected for a period determined by the timer, the output of the light fitting is reduced to a lower level, which can be adjusted by means of the potentiometer. If the ambient light level is above the lower level, the light fitting is turned off. |