Intermatic Button Thermal Phot...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$76.70
$21.26
Intermatic K4021C Button Thermal Photocontrol, 120 V

Intermatic Button Thermal Photocontrol 120V Outdoor Lighting Control with Delay Feature

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Model: K4021C
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In Stock (leaves warehouse same day if ordered before 3pm ET)

$76.70
$21.26
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Intermatic Button Thermal Photocontrol 120V Outdoor Lighting Control with Delay Feature

Professional Automatic Dusk-to-Dawn Lighting Control

The Intermatic Button Thermal Photocontrol delivers reliable 120V outdoor lighting automation with mechanical bimetal switch technology and Cadmium Sulfide photocell sensing. This compact photocontrol fits standard outlet boxes, post lamps, wall packs and other lighting fixtures with its 3/8"-18 NPSM threaded stem design. The integrated delay feature prevents unwanted OFF switching for consistent performance in outdoor lighting applications.

Professional Features & Benefits

  • 120V AC Operation: Compatible with standard residential and commercial voltage systems for versatile installation options
  • Mechanical Bimetal Switch: Provides reliable thermal switching action with proven durability for long-term outdoor service
  • Cadmium Sulfide Photocell: Delivers accurate light sensing for precise dusk-to-dawn operation in varying conditions
  • Compact Design: Fits standard outlet boxes, post lamps, and wall packs with space-efficient 0.938" width profile
  • Delay Feature: Prevents unwanted OFF switching from temporary light sources or brief shadows for stable operation
  • Threaded Stem Mount: 3/8"-18 NPSM threading with 3/4" length provides secure installation with locking nut and washer gasket
  • 2-Year Warranty: Limited warranty coverage ensures reliable performance and professional peace of mind

Technical Specifications

  • Applications: Outdoor Lighting Control
  • Country Of Origin: Mexico
  • Depth: 0.811 in
  • Input Voltage Rating Range S : 120 VAC, 50/60 Hz
  • Marketing Description: These photocontrols install within lighting fixtures, post lamps, or in-wall boxes to provide dusk-
  • Product Color: Gray
  • Product Height: 1.813 in
  • Product Length: NA NA
  • Product Weight: NA lbs
  • Product Width: 0.938 in
  • Warranty Period: 2-Year limited

Professional Applications

  • Residential Outdoor Lighting Systems
  • Commercial Building Perimeter Lighting
  • Post Lamp and Decorative Fixture Control
  • Wall Pack and Security Lighting
  • Parking Lot and Walkway Illumination
  • Landscape and Architectural Lighting
  • Municipal and Public Area Lighting

Why Choose Intermatic Quality?

Intermatic photocontrols deliver proven reliability with mechanical bimetal switch technology and 2-year limited warranty coverage. The gray finish and compact design ensure professional appearance while the threaded stem mounting system provides secure installation in diverse outdoor lighting applications.

Manufacturer Resources

Product Specs

Application:
Outdoor Lighting Control
Country Of Origin:
Mexico
Input Voltage Rating Range S :
120 VAC, 50/60 Hz
Marketing Description:
These photocontrols install within lighting fixtures, post lamps, or in-wall boxes to provide dusk-
Product Color:
Grey
Product Height:
1.813 in
Product Length:
NA NA
Product Weight:
NA lbs
Product Width:
0.938 in
Warranty Period:
2-Year limited
Product Depth:
0.811 in

Intermatic K4021C – Frequently Asked Questions

1) What thread does the Intermatic K4021C photocontrol stem use, and will it screw into my fixture's photocell hole?
The stem on the K4021C button photocontrol is 3/8"-18 NPSM, 3/4 inch long, and comes with a locking nut and washer gasket. That is the standard button-type photocell thread used on post lamps, wall packs, and fixture knockouts, so if your fixture or in-wall box has a 3/8 inch threaded photocell hole, this mounts straight into it and the gasket seals the outdoor side.
2) Will an Intermatic K4021C button photocontrol work on 277V or 240V lighting?
No. The K4021C is a 120 VAC only device, rated 120 VAC at 50/60 Hz. Putting it on a 277V wall pack circuit or a 240V feed will destroy it. For 277V or multi-voltage site lighting you need a photocontrol rated for that voltage, not this button model.
3) Why does my photocell keep flickering off when a car's headlights hit it, and does the K4021C fix that?
That is short-cycling from a transient light source. The K4021C uses a thermal bimetal switch with a built in delay, so a brief flash of headlights or a passing shadow will not toggle the fixture. The lamp stays on until the ambient light level genuinely changes. This is the reason to pick a thermal button control over a snap-acting one on a driveway or parking lot pole.
4) What is the difference between a button thermal photocontrol like this and a twist-lock photocell?
Two different mounting systems. The K4021C is a button type: it threads through a 3/8"-18 NPSM hole in the fixture or an in-wall box and wires internally. A twist-lock control needs a three-prong receptacle on top of the fixture head and cannot be used in a threaded hole. If your wall pack or post lamp has a small round threaded knockout, you need this button style. If it has a locking receptacle, this one will not mate to it.
5) Will the Intermatic K4021C button photocontrol fit inside a shallow fixture housing or outlet box?
It is a small button-style control: 1.813 in by 0.938 in by 0.811 in. That clears the inside of most standard outlet boxes, post lamp bases, and wall pack housings. Measure the depth behind your photocell hole against the 0.811 in figure if the housing is tight, since the body sits behind the mounting surface.
6) What model do I order for an Intermatic 120V button photocontrol, and what color is it?
Order model K4021C. It is the Intermatic button thermal photocontrol for 120V outdoor lighting, finished in grey so it disappears against most fixture housings and cast aluminum post lamp bases.
7) Can I use the K4021C to switch a whole bank of parking lot lights, or only one fixture?
The K4021C is a fixture-level control. It is built to mount inside the lighting fixture, a post lamp, or an in-wall box and switch that outdoor lighting circuit at 120V. For standardizing a property, that means one control per fixture rather than one master control for a bank, which is the tradeoff: each head runs on its own dusk-to-dawn sensing and a single failed cell only affects that head.
8) Does the Intermatic K4021C photocontrol come with mounting hardware, or do I need to buy a gasket and nut?
The locking nut and washer gasket ship with the control, so the threaded stem installation is complete out of the box. You supply nothing but the wire connections and the 3/8 inch mounting hole in the fixture or box.
9) What kind of sensor is in the Intermatic K4021C, and how does it decide when to turn lights on?
A cadmium sulfide photocell does the light sensing and a mechanical bimetal element does the switching. As ambient light drops at dusk the cell's resistance changes and the bimetal contacts close, energizing the fixture; at dawn it reverses. The thermal element is what gives the control its delay rather than an instantaneous snap, which is why brief light changes do not cycle the lamp.
10) Where is the Intermatic K4021C photocontrol made?
The K4021C button photocontrol is manufactured in Mexico. Useful if your agency or institutional purchase requires country of origin on the submittal.
How fast can I get the Intermatic K4021C delivered?
Most orders ship the same day from our distribution partners, with quick delivery throughout the continental U.S. Need it urgently? Contact Us for expedited shipping options.
Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit, reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the Intermatic K4021C come with a warranty?
Absolutely. The Intermatic K4021C is backed by a manufacturer’s warranty. For full warranty terms, check the product documentation or Contact Us.
How do I get technical support or installation help for the Intermatic K4021C?
You can call, text, or email our expert support team for fast answers. We’re here to help with product selection, installation tips, and troubleshooting. Contact Us
Why buy the Intermatic K4021C from ZenSupply?
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