Sunco Dusk to Dawn LED lights include a built in photocell sensor to detect light levels. This turns on the LED in absence of light and off again when light is detected.Spacing is needed between multiple Dusk to Dawn (D2D) light bulbs or wall packs so that the light of one will not interfere with another. This prevents light from shining on the sensor of a nearby D2D bulb. Otherwise, it is possible that existing light could fool the D2D sensor into thinking it is daytime and it won’t turn on when it should.To help you avoid this issue, please use the proper spacing provided below when mounting your Dusk to Dawn lights.Dusk to Dawn PAR20, PAR30, PAR38 BulbsSpace D2D PAR bulbs used as downlights or uplights at least 0.5 meters (1.64 ft) apart so they do not interfere with one another.You can also consider:1. Pointing lights away from one another so their beams to do not strike nearby light fixtures and the D2D sensor.2. Using a dual bulb fixture with bulbs pointing in different directions (usually affixed to the side of a wall or in landscaping as uplights and washes).Dusk to Dawn Wall PacksOur LED Wall Packs with Dusk to Dawn perform best when mounted at least 16.4 ft (5m) from a wall, at least 32.8 ft (10m) from another D2D Wall Pack or other light source, and at least 9.84 ft (3m) from the ground.Recommended Spacing:• 9.84 ft (3m) from the ground• 16.4 ft (5m) from a wall• 32.8 ft (10m) from another Wall PackST64 D2D & A19 D2D BulbSunco's A19 LED bulb detects infrared (IR) light. Spacing concerns should only appear when placing more than one A19 LED Bulb in the same fixture.