A Single Pole Double Throw Switch is an electromechanical device that can direct current to one of two paths. It has three terminals: one common terminal (C), and two output terminals usually referred to as normally open (NO) and normally closed (NC). When the switch is in the “open” position, the current flows from the common terminal to the NO terminal, and when it’s in the “closed” position, the current flows from the common terminal to the NC terminal. The switch allows for a circuit to be redirected from one output to another, making it useful for applications where alternating between two circuits is necessary, such as switching between different sets of lights or devices within an electrical system.
The Single Pole Double Throw Switch has only two terminals. The middle terminal is the input terminal(common terminal), and the terminal on the left or right is the output terminal.
what are poles and throws？
The conventional wiring method is as follows: connect the live wire or the positive terminal to the middle input terminal, and connect the output terminal to one terminal of the device. Finally, connect the other terminal of the device with the other end of the input terminal to the power supply.
Single Pole Double Throw Switch SymbolsSingle Pole Double Throw (SPDT) Switch Electrical Circuit
Here is an example of a circuit diagram for a single-pole single-throw switch controlling a light bulb.
At the same time, you can replace the above light bulb with your corresponding device.
Application areas of different voltages
The voltage of the switch is divided into DC switch and AC switch. Different voltages have different application fields. Below I will specifically introduce the application of different voltages.
| Voltage | Application |
| 12V | Automotive Electrical Systems UPS (Uninterruptible Power Supply) Solar Power Systems LED Lighting Portable Electronics |
| 24V | Automotive and Truck Applications Power Tools and Equipment Small Electric Vehicles Industrial Automation Equipment |
| 36V | Electric Bicycles and Scooters Power Tools Small Electric Vehicles |
| 48V | Electric Bicycles and Scooters Electric Vehicles (Light) Energy Storage Systems Power Tools |
| 110V-120V | Residential Power Systems Electronics Power Tools |
| 220V-240V | C ommercial Power Supply |
What are the conventional currents?
| Electric current | Application |
| 0.1A-1A | Tiny electrical flows, often used in low-power devices. |
| 6A | Mid-range currents suitable for more demanding consumer and automotive applications. |
| 10A-16A | Electric bicycles, scooters, higher-powered tools, residential appliances. |
| 20A | Energy storage systems, light EVs, larger power tools. |
| 30A | Small residential power systems, heavy-duty tools, and electronics. |
| 40A | Industrial equipment, HVAC systems, commercial appliances. |
Summary of Applications:
| Configuration | Applications |
|---|---|
| ON OFF | Ligh |
| ON ON | Circuit selecti |
| ON OFF ON | Fan spee |
| (ON) OFF ON | Vehicle |
| (ON) OFF (ON) | Motor direc |
Features
After selecting the voltage, you can choose the specific switch type for your application.
Types of Switches | Features |
 Rocker Switch | A rocker switch features a pivoting mechanism for on/off control, is durable, easy to operate, and comes in various configurations, sizes, and designs, suitable for both residential and industrial applications. |
 Toggle Switch | A toggle switch has a lever that moves up and down to control electrical circuits. It offers a reliable on/off mechanism, comes in various sizes, and is commonly used in industrial and household devices. |
 Electromagnetic Switches | Electromagnetic switches use an electromagnet to control the opening and closing of circuits. They offer precise, remote operation, are commonly used in relays, solenoids, and automated systems for efficient switching. |
 Micro Switch | A micro switch is a small, highly sensitive switch activated by minimal physical force. It provides precise, reliable operation in response to motion, commonly used in safety devices, appliances, and machinery controls. |
 Push Button Switch | A push button switch is a simple on/off mechanism activated by pressing a button. It is compact, easy to operate, and widely used in electronics, appliances, and control panels for various applications. |
 Tactile Switches | Tactile switches provide feedback through a slight “click” when pressed, offering a reliable and responsive action. Compact and durable, they are commonly used in electronic devices, keypads, and control panels. |