What do the “I” and “O” on the power switch mean?

Understanding the Role of a Switch in Electrical Product Design

A switch plays a crucial role in electrical product design by managing the flow of electricity. It essentially acts as a gatekeeper for electrical circuits.

Controlling Power Flow: The primary function of a switch is to control when electricity can flow through a circuit. By closing the switch, you complete the circuit, allowing electricity to power the device. Conversely, opening the switch breaks the circuit, stopping the current and turning the device off.
Enhancing User Control: Switches provide a simple, user-friendly means to safely manage electrical connections, making them indispensable in appliances and electronic devices. They allow users to easily turn equipment on or off, adding convenience and flexibility.
Improving Safety: By breaking the circuit, switches prevent continuous power flow, which can be vital for maintaining safety and preventing electrical hazards. This is particularly important in home and industrial settings where the risk of overheating or short circuits is present.

In summary, switches are fundamental in the design and function of electrical products, offering control, convenience, and safety by opening and closing electrical circuits as needed.

①　There are two symbols "I" and "O" on the power switch of some large equipment. Do you know what these two symbols mean?

"O" is power off, "I" is power on. You can think of "O" as the abbreviation of "off" or "output", which means off and output, and "I" is the abbreviation of "input", that is "Enter" means open.

②　So where did these two symbols come from?

In order to ensure the stable operation of electrical equipment during World War II, it is necessary to unify the switches of electrical equipment in various fields such as the army, navy, air force and logistics, and the standard of the selector switch. In particular, the identification of switches needs to ensure that soldiers and maintenance workers in various countries can recognize and use them correctly after only a few minutes of training.

An engineer thought that the problem could be solved by using the binary code that was commonly used internationally at that time. Because binary "1" means on and "0" means off. So, there will be "I" and "O" on the switch.

In 1973, the International Electrotechnical Commission (IEC) officially suggested that “I” and “O” should be used as the symbols of the power on-off cycle in the technical specifications compiled. These symbols are now widely recognized and appear in the IEC 60417 standard for on/off switch markings. The symbol for ON is “I” (a straight line), signifying that the circuit is closed and power is flowing. Conversely, the symbol for OFF is “O” (a circle), indicating that the circuit is disconnected. These visual cues help users easily identify the operational state of a device. It is important to note that the orientation of these symbols can vary depending on specific equipment standards. Some guidelines may require that the “I” be installed in a vertical position to signify the ON state. In my country, it is also clear that “I” means the circuit is closed (i.e., open), and “O” means the circuit is disconnected (i.e., closed). This intuitive design ensures that users can operate switches with confidence, knowing the exact state of the device they are controlling.

③　How to choose a button switch?

What Are the Different Types of Switches Available?

Switches are essential components in electrical circuits, and selecting the right one depends on your specific needs. Each type of switch serves a unique purpose based on the number of circuits it controls.

Understanding Switch Circuits

At the most basic level, switches can be classified based on how many circuits they manage. A single-pole switch manages one circuit, while a double-pole switch manages two circuits, essentially functioning like two single-pole switches combined.

Key Types of Switches

To make an informed decision, let's explore the primary classifications of switches:

Single-Pole, Single-Throw (SPST)
- Function: This is the simplest type of switch. It operates one circuit and provides an on/off function. It's commonly used for controlling lights where basic functionality is needed.
Single-Pole, Double-Throw (SPDT)
- Function: This switch can route a single circuit to one of two paths. It's ideal for scenarios where you need to switch between two different outputs or devices from a single input source.
Double-Pole, Single-Throw (DPST)
- Function: A DPST switch controls two separate circuits simultaneously. It either opens or closes both circuits at once, often used in industrial settings where dual circuit control is necessary.
Double-Pole, Double-Throw (DPDT)
- Function: This versatile switch can control two separate circuits, each capable of being connected to one of two different outputs. Think of it as two SPDT switches united, suitable for complex circuitry arrangements or reversing motor directions.

Selecting the Right Switch

Choosing the correct switch depends on your project's demands. Consider the number of circuits, the complexity of operations, and the specific applications for which the switch will be used. Understanding these basics will lead you to the perfect switch for your electrical needs.

1. Combined material

Common plastic switches, although insulating, are flammable and prone to safety hazards. It is recommended to choose a switch with stainless steel inlaid on the surface to fundamentally prevent contacts and improve safety.

2. Combine scents

Choose a colorless and odorless PC plastic power switch.

3. Combined logo

Choose products with 3C、CE certification.

4. Combine button sounds

When using the switch, choose a power switch with crisp sound and no stagnation feeling.

5. Combine product appearance

The selection button has a bright, flawless, black-spotted surface. The appearance should be smooth and smooth, and the color should be uniform.

When discussing circuit control, a single-pole switch is used to control a single electrical circuit. Essentially, it's the most straightforward type of light switch you'll encounter. Designed for on/off functions, this switch operates just one line of electrical energy, making it ideal for simple, everyday lighting applications.

In contrast, other switch types, such as double-pole switches, manage more complex setups by controlling two circuits simultaneously. However, if you just need to toggle a single light or appliance, the single-pole switch is your go-to solution.

Its ease of use and installation makes it a favorite for basic home and office electrical systems. Remember, with a single flick, you're directing the flow of electricity through just one circuit, providing the simplicity many households require.

④　How to Install the Power Switch?

1. Before installing the power switch, it is necessary to turn off the main power supply in the home to avoid the danger of contacts;

2. Before installation, check whether the accessories of the power switch are complete;

3. Distinguish the difference between the wires, which are the live wire, the neutral wire, and the ground wire. Combine the wiring method of the power switch pins terminal to correctly link the circuit;

4. After the button switch is installed, use the testing instrument to check to ensure that the switch is normal.

On/off markings on a switch actuator are typically located either at the end of the actuator or directly on its face. The actuator, which is the component used to manually toggle a circuit, often features these markings in a highly visible spot. Generally, the face of the actuator is the most common and easiest place to find these indicators.