K4021C 120V SPST Dusk-To-Dawn

Intermatic Photo Controls provide “dusk-to-dawn” control of street, parking lot, billboard and security lighting. Mounting types include fixed position mounting, stem mounting and twist lock.  With so many different options, Intermatic and Green Electrical Supply have the right Photo Control sensors for your application. Click here to view other Intermatic Dusk-To-Dawn Photo Control Sensors.

LED products work very well with electrical controls such as dusk-to-dawn sensors, daylight harvesting controls, timers, etc.  On the other hand, a compact fluorescent (CFL) requires a non-electronic, or mechanical control.  The problem using any control device with CFL’s is voltage leak. Some photo controls actually leak a small amount of electrical current in the off position. The best way to test if your existing photocell is compatible with CFLs is to measure the voltage at the socket when the sun is shining brightly - a digital meter is required. The voltage should be 0.0VAC. When you see any other reading, it is possible that it is not compatible.  Intermatic's Photo Control series K4000C, K4100 and K4200, mechanical “snap action” type dusk-to-dawn photocells will work well with a CFL. These types of dusk-to-dawn sensors work well with CFL’s because they are either totally on or off and without current leak. Click here to see the Intermatic Photo Controls Brochure.

The Intermatic K4000C Series model number K4021C, dusk-to-dawn photocell is designed to fit into a standard outlet box, post lantern or wall pack.  They are equipped with a 3/8" - 18 threaded side mounting and the lock nut and washer gasket are included.  Each Intermatic K4021C comes with 9" black, white and red leads.  They operate on 120 volt, turn on in the evening when light levels reach 1-5 footcandles and turn off in the morning when light level readings reach 3-15 footcandles.  The physical dimensions of the Intermatic K4021C dusk-to-dawn photocell is 1 5/16” wide by 1 13/16” long by 13/16” deep. They are UL and CSA approved and California Title 24 compliant, carry a 5 year warranty and are gray in color. Click here to see the Intermatic Photo Controls Instruction Sheet.

Tips To Optimize Photocell Performance

Do not face the photocell into the midday sun. If the photo control is installed on the south side of a building, face the photocell east or west or point the photo control down toward the ground.  The best direction to face the photo control is north. 

Do not face the photocell where it can see artificial light. Light from windows, signs, street lights, etc., will cause the photo control not to switch on.  The photo control should not be positioned so that it sees the light it is controlling (or reflected light - like off of your white siding or white painted soffit overhang).  These conditions will cause the light to cycle on and off.

Do not install the photo control with wires up unless there is NO POSSIBILITY of water

entering the photo control around the wires. The photo control must be installed in an approved weatherproof box. Do not attempt to caulk around the wires. Installing a Photocell below the box is WRONG! Photocells installed on top of the Box is RIGHT! Any Photo Control installed by the side of the weatherproof box is: ACCEPTABLE!

When you are testing the photocell, be sure to turn on the power (load will come on)

and wait up to 5 minutes for the photocell to switch load off. For further testing cover the photo control completely with black tape or another dark material to simulate night conditions. If you can’t cover the control with tape, try covering the photo control with the shipping carton to simulate night conditions.