What is a Garage Door Safety Sensor ?

What is a Garage Door Safety Sensor ?

The safety sensor on your automatic garage door may be small, but it has a big job. Most garage doors weigh at least 500 pounds, sometimes more, which means they are too heavy for most people to move manually. If the door were to close shut on a person or animal, it could result in serious injuries or even death.

This device ensures that your garage door operates correctly and safely, preventing it from closing shut on inanimate objects and people and reducing the chance of severe injuries or damage.


Because of safety issues, the federal government mandated companies that produce garage door openers to install safety devices in order to prevent accidents.”What is a Garage Door Safety Sensor ?”.  Since the law was introduced in the early 1990’s, all garage door openers have implemented door sensors in order to be in compliance with federal regulations.

Although garage door sensors are nearly ubiquitous, many people still don’t how they work. The main function of the photo eyes is to ensure that there is not anything blocking the path of the door when it is closing.

In order for the door to continue closing, the photo eyes must “see each other”, which is a loose way of saying that the ray of the infra-red beam that connects the photo eyes to each other remains uninterrupted. If that ray has been interrupted, the garage door will reverse, opening instead of closing.

Garage door openers can be opened with a remote control, which activates the motorized trolley. While some buttons on garage door openers are wired to the house, others are remote powered, so that you can open your garage door while still in your car. However, most modern garage door openers combine the two technologies for the sake of convenience, allowing you the ability to use both features.

Retroreflective Garage Door Safety Sensors

While the most common type of safety sensor uses an infrared beam, there’s also the retroreflective sensor. Though this type of sensor uses the same “line of sight” and infrared beam technology, it consolidates space by having the device’s emitter and receiver in the same solitary unit. Instead of two units, one unit and a retroreflector on the other side sends the beam back to the receiver.

Troubleshooting Common Problems with Safety Sensors

If the safety sensor on your garage door is malfunctioning or broken, don’t wait another day. It’s essential to fix it as quickly as possible to ensure complete safety for you and your family. For severely damaged sensors, of course, it’s best to call a professional or purchase a replacement. However, sometimes there are minor issues you can quickly fix to get your sensor working again.

Here are some tips for troubleshooting a problematic safety sensor :

Check the Garage Door Light Sensors

Problems with the light sensors are common with garage door safety devices. You can check your light sensors by attempting to close the garage door, at which point the exterior LED lights should blink and stay green. If they stay red, the garage door is out of alignment. If you notice the light staying red, check for loose mounting brackets or screws.

Reset the Power Supply

The lights on your safety sensor are integral to its operation and should always remain on. If you notice that one or both of the lights on your sensors are off, they probably aren’t receiving any power. Look for loose connections and try turning the power source on and off.

Clear Any Obstructions

Remember, the purpose of a safety sensor is to prevent the garage door from closing if any objects are blocking the infrared beam connection. It may sound simple, but things like leaves, rocks, dirt, tools, etc., can often pile up, blocking the beam from connecting. Keep the area around your safety sensor completely clear.

Improper Positioning

Another common issue that can prevent garage door openers from working is improper alignment of the sensors. Remember, the infrared beam must be able to connect for the sensor to function. So, if one of the photo eye devices is in the wrong place – such as too high or too low – it won’t be able to make the proper connection. Check that each sensor is level and making a complete connection.

Pinched Wires:

In most cases, it has been found that the sensors might have pinched wires. This causes a voltage drop leading to inconsistent door operation. The only remedy for pinched wires is 100% system replacement from a thorough garage doors professional. It is advised to disable the electric opener until the repair work is done to avoid any property damage or injury.

Dirty Lenses:

The photo-eye of garage door sensors is made of superior-quality glass. Over time, these sensors tend to get dirty. You can manually clean it with a mild cleanser and a soft cloth to eradicate the sensor issue.

How to Align Garage Door Sensors

After verifying that you have faulty garage door sensors, you will need to adjust the alignment. When your garage door sensors do not align properly, your receiver will not detect input from the emitter. This will cause your garage doors to remain open regardless of any other issues.

Luckily, garage door alignment does not require a professional. With the right tools and some hands-on initiative, you can ensure your garage door opens and closes correctly in no time at all.

Necessary Tools for Aligning Garage Door Sensors

Before making adjustments to your garage door alignment, you must gather the necessary tools for the job.

Ensure you have the following tools and materials :

  • Protective gloves
  • Standard screwdriver
  • Cotton string
  • Beam level

Steps to Align Garage Door Sensors

After you’ve collected the necessary tools, follow this

step-by-step guide for garage door sensor alignment:

Step 1: Turn Off the Power

Locate the breaker box in your home and trip the fuse that supplies power to your garage. This will cut off the electricity to your sensors and allow a safe environment while working. Simply unplug the power cord from the provided electricity outlet for manually powered sensors.

To ensure your personal safety as you work, always wear protective gloves, particularly electricity-resistant gloves, when handling electric wires.

Helpful Tip:

Electrically insulated gloves include a “class” rating. When shopping for protective gloves, find a pair with a “Class 0” rating that can withstand up to 500 volts. This class provides adequate protection for garage door alignment and adjusting sensors.

Step 2: Loosening Screws in Sensor Mount

A mounting bracket encases each of the sensors in your garage. Along the side of these mounts, you will find a set of screws that hold your sensors in place. Use your standard screwdriver to loosen each set of screws in the mounting brackets.

Do not remove the screws entirely. You will need to leave the screws in place in order to shift the mounting brackets accordingly in the next few steps.

Step 3: Shifting the Mounting Bracket

With the screws now loosened, you can freely manoeuvre your mounting brackets up and down. Lower your garage door sensors as far as possible, using your hands to keep them within the mounting brackets. Avoid using tools such as a wrench to lower the brackets–marks left on the sensor’s surface can disrupt functionality and cause damage to the sensor.

Step 4: Attaching String

With your garage door sensors lowered as far as possible, wrap a piece of string around one of the sensors and its bracket. Form a tight knot so the sensor does not move within the mounting bracket. You will run into alignment issues with the opposite sensor without a tight enough knot and need to start again.

Now run the excess length of your string from one end of the garage door opening to the other. Attach the excess string to the opposite sensor and form another tight knot around the mounting bracket. You should now have a taut line of string running as straight as possible between both garage door sensors.

Step 5: Leveling Your String

With your string in place along the bottom of your garage door frame, you can now check the alignment of your sensors. Take your level and hold it firmly against the bottom of your string. Hold the level in place for a few seconds and see if the string runs level along the garage doorway before removing it.

If your string doesn’t run level, you will need to adjust your sensors again. Slide the mounting brackets one at a time, either upward or downward, as necessary, until your level indicates the proper alignment of your sensors.

Step 6: Fastening Mounting Bracket Screws

With your string running level and your sensors accurately in place, you can now tighten the screws of your mounting brackets. Tighten the screws until your garage door sensors no longer move in place, even when applying pressure.

Tightening the mounting bracket screws can sometimes cause sensors to shift out of place. Use your level one more time to ensure the alignment of your sensors before moving on to the next step.

Helpful Tip:

To avoid going back and forth between sensors during the string and levelling process, find a partner who can help. This allows for easier adjustment of the mounting brackets, especially when you find your string needs re-levelling.

Step 7: Turn the Power On

Once you ensure the proper alignment of your garage door sensors, you can remove your placement string. Find the breaker box and turn the power to your garage back on, or plug in the electric cord for manually powered sensors. Test your newly aligned garage door sensors and see the results of your handiwork.

Garage Door Safety Sensors – Trial & Testing

As soon as you have diagnosed and fixed the garage door safety sensors, it is the correct time to test and take a live trial of your garage door! For that, you will require a few big size cardboard boxes. It is preferred to have big-sized boxes.

Once assembled, start the testing in the following manner:

Start closing the garage door. Now, place the cardboard box in the path of the door. It is an obstacle for the door sensors; hence the door should instantly stop closing and commence its reversal action. If it fails, follow the next step mentioned below.

If you see any ‘blinking’ sensor lights, realignment is needed.Now close the door again and use the second cardboard. If the box gets crushed, clean the photo-eye as per the process mentioned in the previous section.

Next, close the garage door using a third cardboard box. Still, inspect the sensor wiring if the sensors fail to pick up the obstacle lying in their path. Are they broken or damaged? Sometimes, the moisture present in the atmosphere might short-circuit the sensors. Replace the entire garage door safety sensor set.

How to bypass garage door sensor ?

If you want to bypass the garage door sensors, one of the easiest ways to do it is to simply press and hold the garage door button. This will override the sensors, and you will be able to open your garage door. However, this method will only work if the sensors are not damaged.

How do I permanently bypass garage door sensors?

Unscrew wing-nuts holding the sensors and then cut the wires around them. Now, gently remove the device from the pole that keeps it. This is the best method to eliminate garage door sensors completely if nothing else is working.

Canadian and US Laws Require Garage Door Safety Sensors

Garage doors must have safety sensors; it’s mandatory under the law. As of January 1, 1993, all automatic garage doors for residential homes must follow the Underwriters Laboratories Standard for Safety, known as UL 325. The law requires all garage doors to have photo-eye safety sensors or a similar safety device.

Flash forward a few years to 2017, when Canada and the US created a bi-national standard for residential garage doors, changing the requirements for construction, installation, testing, etc. The primary purpose of these changes is to increase safety and security for families with automatic garage doors and prevent accidents from occurring.

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