Category: Blog

What is a Photocell Sensor?

Automatic lighting, such as streetlights, often uses photocell sensors—also known as photoeyes—to sense how much ambient light there is. Once the photocell detects low enough light levels, the light turns on or conversely, rising external light levels will turn the light off.

The photocell is made up of a resistor attached to photosensitive plates. As more light hits the plates, the resistance (the amount of current that travels through the resistor) changes, turning the light on and off. This technology is convenient for all types of outdoor locations.

With no user input required, there’s no concern about setting timers or forgetting to turn the lights on. The photocell acts similar to how a light switch would—as such, photocell sensors are also sometimes called photoelectric switches.

Photocells work all year round, activating at dusk and turning off at dawn, even when the days are longer in summer or shorter in winter. As they sense the amount of light rather than operating at a set time, they don’t need to be adjusted when sunrise or sunset shifts with the seasons.

Many outdoor lighting setups use motion sensors. However, photocell sensors and motion sensors typically serve different purposes. While a motion sensor might be useful to keep stray animals away from dumpsters and garbage cans, for example, a photocell can keep a parking lot safely and consistently lit for long periods of time.

How to Install a Photocell Sensor for Outdoor Use

The following steps will guide you through the installation of a photocell sensor. This project requires some electrical work, so if you do not feel confident or safe performing these tasks, you should contact an electrician to install the photocell for you.

  1. Turn off the circuit breaker to your outside light. If you do not know which breaker powers your light, turn off all breakers in the building to ensure that power is cut off. Double check that the power is off by flipping the switch to the outdoor light to make sure it doesn’t turn on.
  2. Disassemble the housing that contains your exterior light. You may want to document how it comes apart with photographs so that you can easily put it back together.
  3. You should see two black wires on the photocell. Those black wires need to be tapped in to the black wire that runs between the light fixture and your structure’s main power. Disconnect the black wire going from the house to the light fixture.
  4. Connect one black wire on the photocell to the black wire that comes from the building. Be sure to twist the exposed copper wire so that it forms a tight connection.
  5. Connect the second black wire on the photocell to the black wire on your light fixture, making sure that the copper wire is twisted together completely.
  6. Cover the new connections you made with electrical caps. Ensure that the cap is tight around the wires.
  7. Tape your connections completely with electrical tape. Make sure that there are no exposed copper wires.
  8. To test the photocell, turn the power back on at the breaker. Make sure that the light switch is in the on position. Cover the photocell with your hand—if the light turns on when the photocell is covered, your photocell is working properly.
  9. Finish installing the photocell by putting your light fixture back together.

If you are installing a new light fixture then the procedure is similar to the one above. To install a new light fixture, you may need the following:

  • The new photoelectric switch
  • Wire strippers
  • Needle nose pliers
  • A screwdriver
  • A voltage tester
  • Electrical tape
  • Wire nuts
  • Silicone sealant

Steps for installing a new fixture:

  • Turn off the power at the circuit breaker.
  • Remove the existing light fixture.
  • Install the new light fixture with the pre-installed photoelectric switch using the mounting instructions that come with it.
  • To wire your new light fixture, use your pliers to cut about 3/8″ of insulation away from the wires. Twist together the black wire of the light fixture and the black wire of your house. Cover the new connection with a wire nut and make sure it is tight. Do the same thing with the white wires. Always connect black wires to black wires and white wires to white wires.
  • Cover all connections with electrical tape and tuck all the wires away.
  • Finish installing your light fixture per the manufacturer’s instructions.
  • Once everything is assembled, test your light as shown above.

ATG Electronics provides photocells that will fit in a variety of places, including outlet boxes, post lamps, or outdoor lights. Our products are well constructed and feature long service lives. If you are interested in photocells for LED lighting, please contact us.

Proper lighting plays an important role in the aesthetic and ambiance of an indoor space. For businesses and commercial facilities it is crucial to give attention to the layouts for lighting. Plentiful, uniform lighting improves visibility and reduces eye strain for office workers, in particular. As such, a well-lit office may improve overall productivity.

Businesses are increasingly adopting Light Emitting Diode (LED) lights to provide affordable, high-quality lighting in their office space. LED lights consume less electricity than traditional light sources such as incandescent bulbs and fluorescent tubes.

ATG Electronics offers a diverse line of LED lighting and fixtures for indoor office use. We’re one of the top commercial lighting manufacturers and suppliers in the U.S. and it’s because of our commitment to excellence that we provide products that are efficient, durable, and register well on what’s known as the Color Rendering Index (CRI).

What is the Color Rendering Index?

Consider the direct impact lighting can have on employees. While subjective assessments of light quality are important, an objective measure helps decision makers select an optimal lighting solution for their application and environment.

The Color Rendering Index (CRI) offers a way to quantify the quality of light. The CRI uses eight pastel colors to determine how a solid-state light source renders color. The CRI operates on the following principle: If a light source renders the eight standard pastel colors well, it will also render all colors well.

A light source’s CRI ranges from 0-100. This number indicates how well a specific light source shows colors in comparison to a standard light. For example, most natural daylight has a CRI of about 75. The scale works as follows:

  • The closer the CRI is to 100, the better the light source is at accurately rendering colors.
  • A CRI value from 90-100 is considered excellent.
  • CRI values between 60-85 are considered good.
  • CRI values less than 55 are poor at color rendering.

LED lights generally have a CRI of 80-90, which means their light output is very similar to or more optimal than natural daylight. Colors lit by LED lights are almost identical to their color in natural sunlight. At the same time, LED lights can be brighter than natural light and are more cost-effective than conventional light bulbs. Conventional light sources such as fluorescent tubes can render colors very differently than natural light, making them appear artificial and causing undue strain on the human eye.

In addition to color quality, LED lights have a much longer service life than incandescent bulbs or fluorescents. LED lights are an optimal light source for achieving good-to-excellent CRI for your business while keeping expenses low.

Color Rendering Index graph with office lighting rank

Where on the CRI Scale is Office Lighting?

Businesses should strive to make their office lighting as close to natural light as possible. Doing so will improve employee wellness, morale, and productivity. Dim or poor quality lighting not only contributes to physical strain, but can have a greater impact on accomplishing tasks that are tied into your business goals. Simply put: the environment you create is the setting for success.

Research supports these claims. For example, hospital lighting has a direct impact on the performance of nurses.  Another study showed that improving the lighting in post offices tremendously improved the productivity of postal workers.

Daylight has a CRI of around 75, which means businesses should aim to achieve a CRI of 75 or better in their offices. Since LED lights have a CRI of about 85, they provide an optimal choice for commercial office lighting. As they cost less per year of service due to their long life and low power consumption, LED lights also offer additional long-term cost savings.

ATG Electronics is a leader in retrofitting conventional lighting systems with LEDs, helping businesses to improve employee productivity while reducing lighting expenses. Contact us today to discuss your commercial or industrial lighting needs.