Where should a transformer with a photocell be installed?

• A. Out of plain view
• B. Behind a shrub
• C. Where there is ample sun
• D. On the east wall of a structure

Answer: (C)

Photocells depend on detecting ambient light to switch the system on or off at the right times. For reliable operation, the sensor needs an unobstructed view of the sky and consistent daylight exposure. Placing the transformer with the photocell where there is ample sun ensures the sensor isn’t shaded by walls, foliage, or other objects, so it can accurately sense daylight and trigger at dusk and dawn as intended. If it’s out of sight or behind a shrub, shading can make the photocell think it’s darker than it is, causing lights or the controller to operate at the wrong times. An east-facing wall might get morning sun but can be shaded later by the building or nearby plants, leading to unreliable performance. In short, the best placement is where the photocell receives ample sun.