In our daily lives, electrical wiring is often divided into weak and strong current. The concepts of strong and weak current are relative, and the relationship between the two cannot be simply defined by voltage. First, we must understand that weak and strong current are both related and distinct. Specifically, differentiating between strong and weak current requires different perspectives.
About Strong and Weak Current
All weak current is used to transmit signals, such as for internet, telephone, and access control.
Anything else that provides energy to other devices, such as making machines run and lights up, is strong current. These processes convert electrical energy into other types of energy.
Weak Current System: Weak current devices cannot function without strong current, but nitpicking and saying the indicator light on a router is strong current and the network cable is weak current is too complicated. Therefore, we have introduced a new concept: the weak current system.
A router's primary function is to transmit signals, so it belongs to the weak current system. The strong current devices (indicators) on it also belong to this weak current system.
Weak Current Voltage
Let me explain a common misunderstanding about voltage and current in weak current. Weak current can refer to either AC or DC. If it's AC, the voltage won't exceed 36V; if it's DC, the voltage won't exceed 24V.
However, this statement doesn't apply in reverse—that AC voltage not exceeding 36V is weak current, and DC voltage not exceeding 24V is weak current—is incorrect!
It can only be said that electricity used for signal transmission (weak current) will never exceed 36V AC or 24V DC. However, electricity used for energy conversion (strong current) has no voltage restrictions—even a 1.5V DC dry cell battery is considered strong current.
In engineering, strong current generally refers to building electrical installations, lighting, sockets, and distribution rooms. Depending on national standards, construction generally involves 110V or 220V electrical equipment and pipeline installations. Power and lighting circuits.
Weak current refers to equipment used in fire protection and intelligent systems. Generally, low-voltage electricity is used for installed equipment, including fire protection, networking, broadcasting, building intercoms, surveillance and security, building automation, and other safety, control, and information circuits.
How to Distinguish Weak Current from Strong Current
1. The fundamental factor in distinguishing strong from weak current is voltage.
Strong current has a higher voltage, typically greater than or equal to 220V; weak current is voltage below 220V. Strong current conducts electrical energy, while weak current conducts signals. For example, electric shavers and flashlights conduct electrical energy and fall under the strong current category. It is inaccurate to classify something as weak current simply because it uses two dry cell batteries and has a low voltage.
2. High voltage includes strong current, but strong current is not necessarily high voltage; low voltage includes weak current, but weak current is always low voltage; low voltage is not necessarily strong current, and strong current is not necessarily low voltage. Strong current wires use thick plastic insulation, a large-diameter copper core, and the inner copper conductor consists of one or more strands of bare wire. The voltage and current of weak current wires are not large, so the insulation layer is relatively thin, and the diameter of the copper core wire is relatively small. It is composed of more than two strands of insulated thin wires. 3. Conceptually, strong current and weak current are generally easy to distinguish. The main difference is their different uses. Strong current is used as a power source, while weak current is used for information transmission. Specifically, they have the following differences: (1) Different AC frequencies: The frequency of strong current is generally 50Hz (hertz), called "industrial frequency", which means the frequency of industrial electricity: The frequency of weak current is often high frequency or ultra-high frequency, measured in KHz (kilohertz) or MHz (megahertz). (2) Different transmission methods: Strong current is transmitted by transmission lines, while weak current can be transmitted by wired or wireless. Radio is transmitted by electromagnetic waves. (3) Power, voltage and current are different. Strong current power is measured in KW (kilowatts) and MW (megawatts), voltage is measured in V (volts) and KV (kilovolts), and current is measured in A (amperes) and kA (kiloamperes); weak current power is measured in W (watts) and mW (milliwatts), voltage is measured in V (volts) and mV (millivolts), and current is measured in mA (milliamperes) and uA (microamperes). Therefore, its circuit can be constructed with printed circuits or integrated circuits. Of course, there are also high-frequency (hundreds of kHz) and medium-frequency devices in strong current, but the voltage is higher and the current is also larger. For example, flashlights and electric shavers, although the voltage is very low and the power and current are very small, are still strong current. Due to the development of modern technology, weak current has penetrated into the field of strong current, such as power electronic devices and wireless remote controls, but these can only be regarded as the weak current control part of strong current, which is still different from the controlled strong current. When we lay wires, we cannot put these two types of wires together. We must wrap them with tin foil, otherwise the wires will interfere with each other. Therefore, the strong and weak wires must be separated. Only in this way can the service life of the wires be increased. If the strong and weak wires cross, we need to use tape to protect the wires.
