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Time Switch -Types, Working, Need, Installation, How to Select

A time switch is an electronic device that has control of the loads & has an automatic switch on and off after a preset time. This switching on/off saves energy when compared to operations without a time switch where the loads will be permanently on. Time switches are also known as timer or timer contactor which is used to control an electric switch.

What is Time Switch?


A Time Switch, also referred to as a timer switch or programmable timer, is a device or system designed to control the timing of electrical appliances or equipment. Its purpose is to enable automated on/off functionality for devices based on predetermined schedules, offering convenience, energy efficiency, and security.

Time switches find applications in various domains, including home automation, lighting systems, HVAC systems, and industrial processes. By automating the operation of devices, they streamline processes and improve efficiency.

Time switches can be installed in residential and commercial buildings in order to control the lighting systems of shops, fountains, public gardens, schools, offices, heating systems and irrigation systems. Users can configure time switches to activate or deactivate devices at specific times of the day or night. Additionally, they can program recurring schedules, such as daily, weekly, or monthly cycles. Some advanced models may incorporate features like daylight saving time adjustments, battery backup, and override functions for manual control.

Types of Time Switches

In present days, Time Switches are available in many types, mainly –

Analog or Mechanical 

Analog or Mechanical-TimeSwitch

Analog or Mechanical time switches rely on clockwork or electro-mechanical mechanisms to regulate the timing of electrical circuits. They typically feature rotating dials or pins that can be manually adjusted to specific times. As the dial or pins rotate, they activate or deactivate the connected devices based on the predetermined schedule. Mechanical time switches are known for their simplicity and affordability.

Digital Time Switch


Digital programmable time switches utilize electronic controls and provide advanced programming capabilities compared to mechanical switches. They usually feature an LCD or LED display along with a keypad for easy programming. Digital time switches allow users to set specific on/off times, durations, and even specific days of the week. They often offer multiple programmable channels to control several devices simultaneously. These digital switches are accurate and has smaller switching times.

Astronomic Time Switch


Astronomical time switches incorporate location-based information to automatically adjust the switching times according to sunrise and sunset times. These switches utilize an astronomical algorithm and typically require latitude and longitude coordinates for accurate operation. Astronomical time switches are commonly used for outdoor lighting systems or applications where the timing needs to synchronize with daylight.

Apparently, these switches control the lights based on the calculations by turning them on and off. According to the fixed weekly plan, these switches control the loads automatically. These switches mainly include street light control, HVAC, pumps, fans, livestock feeders, poultry equipment, heating or ventilation equipment.

Wireless Time Switch

Wireless Time SwitchWireless time switches eliminate the need for physical wiring connections. They employ wireless communication technologies such as Wi-Fi or Bluetooth to connect with other devices or a central control system. Wireless time switches provide flexibility in terms of installation and control, as they can be easily integrated into existing automation systems or controlled remotely through mobile apps.

Industrial Time Switch

Industrial Time SwitchIndustrial time switches are designed to withstand demanding environments and heavy-duty applications. They feature sturdy construction to handle high electrical loads and often include additional features such as voltage protection and surge suppression. Industrial time switches are compatible with industrial control systems and are suitable for use in factories, manufacturing plants, and other industrial settings.

Plug-in Timer

Plug-in TimerPlug-in timers are compact devices that can be directly plugged into a power outlet. They are commonly used for controlling devices such as lamps, fans, or holiday lights. Plug-in timers typically offer basic programming options and are suitable for simple scheduling needs.

How Time Switch Works?

Working of Time Switch

The following is a detailed explanation of how a time switch works:

Clock Mechanism

A time switch incorporates an internal clock mechanism, which can be based on either a quartz crystal oscillator or an electronic circuit. This mechanism ensures accurate timekeeping.


Users can program the time switch through various means such as buttons, switches, digital displays, or mobile apps. This interface allows them to set specific on/off times or schedules for the connected devices. Different time periods can be assigned for different days or repeated cycles can be created.

Time Comparison

It continuously compares the current time provided by its internal clock mechanism with the programmed schedules. It checks whether the current time matches any of the programmed on/off times or active schedules.

Switching Operation

When the current time aligns with a programmed schedule, the time switch triggers its switching mechanism. This mechanism, which may be a mechanical switch or an electronic relay, controls the power supply to the connected device or system.

Power Control

If the current time corresponds to the programmed “on” time, the time switch activates the power supply, turning on the connected device or system. Similarly, if the current time matches the programmed “off” time, the time switch cuts off the power supply, turning off the connected device.


The time switch continually repeats this process, continually monitoring the current time and comparing it with the programmed schedules. It carries out the switching operation based on the programmed settings until the timer is deactivated or modifications are made to the programming.



The time switch can be used in following areas:-

Office or Workplace

Before the employees come to work, the packing machine will be warmed so that they can start their work immediately.

School or Colleges

The chimes will be sounded at the beginning of the classes, during lunch break and the end of the classes.

Recreation Area Swimming Pool

The water pump of a swimming pool is controlled by a time switch. It allows the different jets to be managed separately.

Water Tank

As per the programmed setting, the water pump is controlled by the electromechanical time switch.

Heating Device

The heating device are spontaneously controlled by the time switch as per the selected program.

Lighting of Buildings or Monuments

The lightings for the building and monuments in the cities are arranged and controlled by time switch. They provide wide range of functions to meet the requirements of the effects required.

Garden or Backyard

In the garden, the irrigation pumps can be controlled using programmed setting.

Church or Religious Place

The church bells are controlled with advanced functions which allows the user to control the breaks between one stroke and the net is required.

Water Fountain

The water pump system in the fountains are controlled by the time switch that makes water like a sparkling waterfall in a very simple way.

Special Weekly or Annual Program

A weekly and annual program are defined by a time switch and advertising signs runs at preset times.

Road Safety Barriers

In the certain days of the year, the road safety barriers access to unauthorized areas can be controlled by an hourly program in the time switch.

Electric Fences

The electric fence is controlled by time switch in order to prevent unknown people or animals to access the areas during night. It keeps activated at preset times of the day.

Importance of Time Switches

  • It saves money on energy costs, improves home comfort and makes our life easier.
  • It is an easy way to automate the lights, water heaters and other electronic appliances in order to operate when the electricity rates are lower.
  • Few timers even have built in weather sensors which adjust the switching times as per the temperature outside.

Selection Parameters   

Here, are some the parameters to be considered while selecting the time switch-

  • Switch types (Analog or digital)
  • Rated Voltage
  • Contact Type (1NO/1NC)
  • Rated frequency
  • Setting Step (Ex 15mins, 1hr)
  • Power Consumption
  • Maximum switching power
  • Operating and storage temperature

Installation of Time Switch

To install a time switch, follow these steps:

1. Turn off the power

Before starting the installation, ensure that the power to the circuit or device you’ll be connecting the time switch to is turned off. Locate the circuit breaker or fuse box and switch off the corresponding breaker or remove the fuse.

2. Remove the existing switch or outlet cover

If you’re replacing a switch or outlet with a time switch, carefully remove the cover plate by unscrewing the screws that hold it in place. Keep the screws in a safe place for later use.

3. Confirm the power is off

To ensure safety, use a non-contact voltage tester to verify that the power is indeed off. This step is crucial to prevent any electrical accidents.

4. Disconnect the existing switch or outlet

Disconnect the wires connected to the existing switch or outlet. Typically, you will find three wires: a black (hot) wire, a white (neutral) wire, and a bare copper or green (ground) wire. Loosen the screws securing the wires and disconnect them, remembering the location of each wire.

5. Prepare the time switch

Familiarize yourself with the manufacturer’s instructions specific to your time switch model. Some time switches may require additional steps for programming or configuration before installation.

6. Connect the time switch

Connect the wires from the time switch to their corresponding counterparts in the electrical box. Usually, you will connect the black wire from the switch to the hot wire, the white wire to the neutral wire, and the bare copper or green wire to the ground wire. Follow its manufacturer’s instructions regarding wire connectors or terminal screws.

7. Mount the time switch

Securely attach it to the electrical box using the provided screws or mounting brackets, ensuring it is firmly in place.

8. Install the cover plate

Position the cover plate over the time switch and fasten it using the screws that were removed earlier.

9. Restore the power

Return to the circuit breaker or fuse box and switch on the power to the circuit. Follow the manufacturer’s instructions to set the time and schedule on the time switch.

Note: Remember that these are general installation steps, and specific instructions may vary depending on the model and manufacturer of the time switch. Always refer to the provided installation manual and adhere to the guidelines outlined by the manufacturer for your particular time switch. If you are uncertain or uncomfortable with the installation process, it is recommended to seek assistance from a licensed electrician.

Advantages of Time Switches

Below are some of the advantages:-

  • Easy installation and simple to use.
  • The time switches are strong, reliable and low-cost.
  • They provide various options and available with sensors.
  • They have visual appealing design and slimmer.
  • They are flexible and safe.
  • They are helpful in connecting Christmas lights automatically.
  • Conservation of power and money.
  • Enhancement of travel experience.
  • Improvement in farm productivity.
  • It turns lights ON and OFF at fixed times.
  • Timely alerts can be obtained.
  • Appliances can be managed easily.

Disadvantages of Time Switches

Below are some the disadvantages:-

  • They need maintenance else the dirt can cause damage to the switch.
  • Depending on the outdoor surrounding conditions, they may get damaged.
  • The mechanical one needs different switchboards and manual control as well.
  • Before the installation the digital time switches need some advance plan at home as they will not be equivalent to normal switchboards.
Read Also:
Class C Amplifier – Working Principle, Applications, Advantages & Disadvantages
What is MOSFET – Working, Types, Applications, Advantages & Disadvantages
Chakrasthitha is a B.E (Medical Electronics) and has work experience in MatLab and Lab View Software as Design Engineer at BCS innovations and Manipal hospital as Biomedical Engineer. She is an author, editor and partner at Electricalfundablog.


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