The Intermatic K4021C is a 120V button-style thermal photocontrol designed for professional electricians and contractors who need dependable dusk-to-dawn switching on outdoor lighting installations. Its compact button form factor makes it a natural fit for post-top lanterns, wall packs, and decorative fixtures where a low-profile mount is preferred. The mechanical bimetal switch paired with a front-mounted Cadmium Sulfide (CdS) photocell delivers proven, field-tested performance, while the built-in sensor time delay prevents nuisance tripping from passing headlights or brief cloud cover — reducing callbacks and keeping installations running exactly as intended.

Specifications

Input Voltage 120 VAC, 50/60 Hz
Mounting Style Button
Stem Size 3/8" diameter, 3/8"-18 NPSM thread
Switch Type Mechanical Bimetal, SPST
Photocell Type Cadmium Sulfide (CdS), Front-mounted sensor
Activation (Turn ON) 1 to 5 fc
Activation (Turn OFF) 3 to 15 fc
Sensor Time Delay 30 sec to 90 sec
Fail Mode ON
Compatible Lamp Types Fluorescent, HID, Incandescent
Incandescent / Tungsten Load 15 A / 1800 W
Magnetic Ballast Load 8.3 A / 1000 VA
Housing Material Polycarbonate (UV resistant)
Colour Grey
Usage Environment Outdoor
Operating Temperature -40°C to 70°C (-40°F to 158°F)
Wire Leads #18 AWG
Certifications cULus, cCSAus, Green Energy, Title 20
Country of Origin Mexico
Warranty 2-Year Limited