Is it necessary to install an over/under-voltage protector？

The necessity and core value of installation
Protecting household appliances from damage: High voltage may burn out internal components of the appliance, while low voltage can cause excessive operating current, coil overheating, or even burnout. The overvoltage and undervoltage protector can automatically cut off the power supply when the voltage is abnormal (usually exceeding 220V ± 10% range), avoiding these damages, especially for expensive equipment such as televisions, refrigerators, and air conditioners. Its protection value far exceeds the cost of the equipment itself, which is about 100 yuan. ‌‌

Improving household electricity safety and preventing fire risks: Abnormal voltage not only damages electrical appliances, but may also reduce the insulation performance of power lines and even directly cause electrical fires. Installing protective devices can add a safety line of defense for household electricity use, effectively reducing such safety hazards. ‌‌
Dealing with voltage fluctuations in the power grid: Although the overall stability of China's power grid has greatly improved, voltage instability still exists in old residential areas, remote areas, or during peak electricity consumption periods. Installing protectors can cope with these uncontrollable voltage fluctuations and provide continuous protection. ‌‌
Compliance with design specifications and reduction of liability risks: According to the "Code for Electrical Design of Residential Buildings" (JGJ242-2011), each residential unit should be equipped with self recovering overvoltage and undervoltage protection appliances. Although strict legal provisions do not require users to install it in all situations, following regulations can enhance security. If not installed, users may be held responsible for any property damage or personal injury caused by voltage issues. ‌‌
Working principle, type and installation points
Core function and type: Over Under Voltage Protector (OUPA) can automatically detect the line voltage. When the voltage exceeds the set value, it will automatically disconnect the circuit. When the voltage returns to normal, it will automatically or manually close. The commonly used in households is a self resetting overvoltage and undervoltage protector, which can automatically restore power after the voltage is restored, without the need for manual operation, making it more convenient. ‌‌
Proper installation is crucial:
Installation location: It should be installed after the main switch of the household distribution box. ‌‌
Wiring direction: Pay attention to the markings on the top and bottom or bottom and top of the protector, and strictly follow the "IN" and "OUT" or "input" and "output" markings for wiring. ‌‌
Distinguishing between live and neutral wires: Ensure that the L end is connected to the live wire and the N end is connected to the neutral wire. If connected in reverse (L to neutral wire, N to live wire), although the protection function may still work, it will disconnect the neutral wire instead of the live wire, causing the load to remain live and posing a safety hazard. ‌‌