The photoelectric switch LP-403 is applicable to control the street lighting, passage lighting and doorway lighting automaticall y in  accordance with the ambient lighting level. This product is designed with electronic circuits. Its quicker response with time delay of  3-10 seconds offers easy-to-test feature. Especially, model LP-403C provides a wide voltage range for customer applications under  almost power supplies.  Further, a preset 3-10 seconds time-delay might avoid mis-operation due to spotlight or lightning during the night time This product  has been listed by UL Inc and is comply with the Standard for Non-industrial Photoelectric Switches for Lighting Control UL773A.