How does a motion sensor light work?

In our daily life, we always us standard light switch, which is turned on when needed and turned off when we leave. However, standard light switches are inconvenient for us under some certain conditions. For example, at night, when you enter an unfamiliar garage, you cannot accurately find the position of the switch or when you take you into the laundry carrying a pile of heavy clothes, there is no way to free your hands to turn on the switch. In such cases, The motion sensor switch will automatically help you turn on the switch and turn off the switch when you leave. This is why we have to install motion sensor switches.

The Advantages of motion sensor switch:

  1. Sensitive sensing: accurately distinguish the movement of biological and non-biological bodies, which will reduce the rate of wrong operation
  2. Strong anti-interference: little influence by external natural factors, stable and reliable performance.
  3. Safe and practical: The motion sensor uses zero-crossing on-off technology inside the product, non-contact switch, does not produce sparks, does not interfere with other electrical appliances, its own power consumption is small, its own service life is long and can extend the service life of the load.
  4. Automatic metering: Automatically identify the strength of the ambient light, the light will be on when the lighting requirements are set and there are people, otherwise it will not be on.
  5. Fully automatic induction: automatically turn on the lights after sensing a person, the lights are on when the person is on, and the lights are off when the person is walking, safe and energy-saving, free from external factors such as sound and objects.
  6. Automatic random delay: When a person is active in the sensing range, the switch is always on, and will not automatically turn off until the person leaves


The principle of motion sensor switch:

Motion sensor switch is also called pyroelectric human body sensor switch or infrared smart switch. A sensor that operates according to the infrared rays of the human body. The body temperature of our human body is between 36-37 degrees Celsius, and it emits infrared rays of specific wavelengths. When people enter the sensing range of the motion sensor switch, the sensor will detect the change in the infrared spectrum and automatically energize the load. If people have been moving within the sensing range of the sensor, the light will always be on. If people leave the sensing range , Then the sensor cannot detect the change of the infrared spectrum, and will automatically turn off the load after a few seconds delay. The motion induction switch is mainly composed of an infrared sensor that converts heat energy into electrical energy and a dedicated circuit integrated circuit. In this way, the purpose of turning on the lights when people go, and turning off the lights when people go.

Application scenarios of motion sensor switches:

  1. Used in meeting rooms, office areas, toilets, basements. It can make people turn on the lights and turn off the lights when they leave, which greatly avoids waste, saves energy for you, and saves you the pain of forgetting to turn off the lights.
  2. Used in disinfection room. When people come, the disinfection equipment is automatically turned off, and when people go, the equipment is automatically turned on. Escort your health.
  3. Used in hotels, guesthouses, etc. Instead of the existing card to get electricity, you can also monitor the dynamics of the room. When people come, the power is turned on automatically, and when people go, the main gate is automatically closed. Full of humanity.
  4. Used in the bedroom. It can dim the light slowly and then turn it off, or it can dim the light slowly.
  5. Used for air conditioning. When you fall asleep at night, or go out during the day and forget to turn off the air conditioner, it will "monitor" all this and send a signal to your air conditioner that it is time to rest.
  6. Used in school and community corridors and garages. It can achieve full light when people come and half light when people walk, and save energy greatly under the premise of ensuring safety.


Take SOK Motion Sensor as an example for better understanding

The Characteristic of SOK Motion Sensor:

Three modes for options: ON (always on), OFF (always off), PIR (Pyroelectric Infrared reacting/sensing). You can switch between different modes easily by the rod at the front plate of the product, to satisfy different circumstances’ need.

This product is pyroelectric infrared sensor with customized IC chip. Excellent performance against interference and high sensitivity is guaranteed.

When working under PIR mode, light is controlled automatically by pyroelectric infrared sensor. When people come, light will be on; when people leave, light will be off with time-delay. When the circumstance is bright enough, switch will keep the light off in order to save power.

When working under PIR mode, if people keep moving in the sensible district, light will keep on; time-delay counts from the last sensible moving.

This product is with LED indicator. When the power is on, LED indicator will be on; when the power is off, LED indicator will be off.


SOK Human Sensor Parameters:

Subject 3L 2L
Working Voltage 180-250V~ 50 /60Hz
Output Power Incandescent Lamp: 0~400W

Fluorescent Lamp: 0~60VA

LED Lamp: 0-40VA

Incandescent Lamp: 5~200W

Fluorescent Lamp: 5~50VA

LED Lamp: 5-30VA

Sensible Angle 110°
Sensible Distance 5-7 meters (25°C)
Light Sensitivity 3-7LUX (adjustable)
Time-delay 30-260 seconds (adjustable)
Dimension 82*82*50mm
Working temperature -20~50°C
Working Humidity 10%~90%RH


How to install a motion sensor

Please follow the diagram below to install this product:


3L model 2L model


Using Instruction:

After wiring appropriately according to the above diagram, toggle to the mode which you need by the rod on the front plate.

Remove the front plate, you can see two cross groove at the back of front panel. Under PIR mode, you can adjust the lighting sensitivity and time-delay by rotating the cross. Factory setting is lowest lighting sensitivity and shortest time-delay. Please follow the instruction below to adjust:

Adjust lighting sensitivity:

Rotate the cross above the icon in clockwise direction to raise the lighting sensitivity, while rotate the cross in anticlockwise direction to lower the lighting sensitivity;

Adjust time-delay

Rotate the cross above the icon in clockwise direction to prolong the time-delay, while rotate the cross in anticlockwise direction to shorten the time-delay;

Need to pay attention to when installing:

To avoid electric shock, only professional technician is allowed to install or disassemble this product.

Please strictly follow the electric scheme printed at the back of the product for installation, in order to avoid any serious problem caused by short-circuit or overload.

When this product is working under PIR mode, please make sure the cambered surface is parallel to people’s moving direction. Otherwise, the sensible distance will be less than the described parameter, or the sensor will fail to detect people’s moving.

This product detect moving by sensor against the variation of human’s temperature, so it may be affected by circumstance or other factors such like circumstance temperature, people’s moving speed and direction, the cloth they are wearing, and the detecting district.

Keep away from the controlled light, heat source, entrance or outlet of cold or hot air, ventilation outlet, or any place directly glared by strong light.

Frequent switching will shorten the light’s life-span, especially for the fluorescent light. For the application district where needs to switch on/off the lighting frequently, we suggest to use resistance-type load, such like incandescent light.

This product is for wall mounting. The installation place should be no less than 1 meters away from the light.

The height for installation should be 1.4 meters ~ 1.6 meters. Please note the installation direction, and please install in the place where it is easy to detect people’s moving.