Generally speaking, the main reason that affects the safety of household appliances during lightning season is the invasion of induced lightning. Induced lightning refers to the lightning electromagnetic pulse generated on various metal pipes and lines entering the building when a lightning strike occurs. For a home, there are four main ways to induce lightning intrusion: power lines, telephone lines, cable TV or wireless TV antenna feeders, house exterior walls or pillars. The first three methods are all directly connected to the external lines of household appliances, and are more harmful when connected overhead. Due to strong lightning induction, strong lightning electromagnetic pulses will be generated on these overhead conductors, which will directly enter household appliances along these conductors, causing harm. At present, the fourth way to induce lightning intrusion is often ignored, that is, household appliances are not installed at a certain distance from the exterior walls and columns of the building. Because when there is direct or lateral lightning in a building where residents are located, strong lightning currents will flow underground along the exterior walls and pillars of the building. During this process, due to the strong lightning current flowing through the exterior walls or columns of the building, electric and magnetic fields are generated in the surrounding space. If household appliances are too close to exterior walls or columns, they may be damaged.
So how can you ensure the safety of household appliances and the people who function in them? Lightning protection technical specifications and experience tell us: First, buildings should be equipped with direct lightning protection facilities in accordance with lightning protection design specifications, such as lightning rods, down conductors, grounded high-voltage arresters, etc. They can direct most of the lightning current into ground discharges. Secondly, the power lines, telephone lines and TV signal lines of the house should be shielded to the ground so that part of the lightning current leaks into the earth.
To ensure safety, users should install overvoltage protectors (also known as high-voltage arresters) for household appliances on corresponding lines. An average household needs three lightning arresters: one is a single-phase power supply arrester, the other is a TV feeder arrester, and the third is a telephone arrester. The function of the lightning arrester is to separate the electromagnetic pulses from the line and limit the voltage, thereby achieving the safety of the household appliances protected by the lightning arrester. Household appliances should be installed as far away from exterior walls or columns as possible. Also pay attention to regularly checking the common ground wire used by household appliances. The casing of most household appliances is connected to this ground wire, and its primary purpose is for personal safety. When installing arresters, all arresters should be connected to the ground wire. If the ground wire is loose or disconnected, the appliance casing may be electrified and the lightning protector may not work properly.
In the past, many people recommended not to use household appliances during thunderstorms, such as unplugging power plugs, antenna plugs and phones during thunderstorms. Of course, this is safer, but it can also be inconvenient sometimes, like when someone calls, does someone answer the phone or not? After unplugging the power, neither the refrigerator nor the air conditioner will work. What should you do if no one is home when there is thunder? Therefore, it is recommended to adopt the above lightning protection method. Of course, when conditions are not ripe, unplugging all plugs is also an emergency measure.
In recent years, many arrester manufacturers have developed and produced high-voltage arresters and over-voltage protectors for some household appliances. Some have added overvoltage protection devices to their products, claiming that they can protect against lightning strikes. Metal oxide arresters need to remind users that lightning protection is required in system engineering, rather than simply adding one or two components or purchasing a lightning-proof power socket.
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