Mike Dolt Enterprises
Mike Dolt Enterprises
User: Papa-Gus, Location: Southern California
Asked on: Tuesday, March 22, 2011 at 8:21 pm EDT
Answered on: Tuesday, May 14, 2024 at 3:07 am EDT
Question: Situation: I have two outdoor fluorescent luminary fixtures, each with a self-contained photocell, installed under a patio cover.Problem: The lamps energize needlessly on cloudy days, often cycling on and off as lighting conditions change; not a desirable condition for compact fluorescent lamps.Objective: I plan to install one single photocell in an ideal location so the lamps energize simultaneously from dusk to dawn as intended.Dilemma: Concerning the NEC, does it matter if I install this new photocell upstream of the wall switch that is used to control the outdoor fixtures or must the wall switch see uninterrupted power directly from the circuit breaker?
According to the National Electrical Code (NEC), there are two acceptable methods for controlling the outdoor fluorescent luminary fixtures using a single photocell
Method 1: Photocell Installed Upstream of the Wall Switch
The photocell is connected to the supply circuit before the wall switch. When the photocell senses darkness, it energizes the circuit, which powers both the luminaries and the wall switch. When the photocell senses daylight, it de-energizes the circuit, turning off both the luminaries and the wall switch.
Method 2: Photocell Installed Downstream of the Wall Switch The wall switch is connected to the supply circuit before the photocell. When the wall switch is turned on, it energizes the circuit, which powers the photocell. The photocell then controls the luminaries, turning them on at dusk and off at dawn.In this situation, both methods are acceptable according to the NEC. However, it is generally preferred to install the photocell upstream of the wall switch. This ensures that the wall switch always has power, even when the photocell is not operating. This allows you to manually override the photocell and turn on the lights even during daylight hours, if necessary.Therefore, you can choose either of the two methods to install the new photocell and control the outdoor fluorescent luminary fixtures simultaneously from dusk to dawn. Flag for review