The day-night sensor has a 20-30 second delay to allow the electronics to adjust to light conditions. It will also energize and de-energize during the first night of installation as it adjusts to conditions and sets its parameters. Ideal exterior applications include wall mounted and pillar lanterns, and perimeter bulkheads. These lamps are also excellent to use as security lights in entrance halls and table lamps. They are sensitive to seasons, unlike timers, so if you arrive home late, you can be can be confident that your day-night sensor will switch on at the appropriate time. Best suited for individual use in fittings with clear glass lenses. Eurolux Day/Night Energy Savers are now fitted with adjustable caps. Fit lamp as normal and adjust the sensor outwards.