Magnetic switches (also called reed switches) are electrical switches that use magnetic force to open or close a circuit, widely used in security systems, home automation, appliances, and industrial equipment. Unlike mechanical switches (which rely on physical pressure to actuate), magnetic switches have no moving parts (except for a small, hermetically sealed reed inside) and are activated by the presence or absence of a magnetic field—making them durable, reliable, and resistant to dust, moisture, and wear.

The core component is a reed switch: two thin, flexible metal reeds (made of ferromagnetic material like iron-nickel alloy) sealed inside a glass tube filled with inert gas (to prevent corrosion). When a magnet is brought near the tube (within 1-2 cm), the reeds are attracted to each other, closing the circuit and activating the device (e.g., a security alarm, a light). When the magnet is removed, the reeds spring apart, opening the circuit. Magnetic switches are often paired with a separate magnet (e.g., a small neodymium magnet mounted on a door) and the reed switch (mounted on the door frame)—this setup is common in door/window security sensors: opening the door moves the magnet away from the switch, triggering an alarm.

Applications are diverse: in home automation, magnetic switches control under-cabinet lights (the light turns on when the cabinet door opens, moving the magnet away); in appliances, they prevent washing machines from operating if the door is open (the magnet on the door keeps the switch closed, allowing operation); in industrial settings, they detect the position of moving parts (e.g., a conveyor belt’s alignment). A home security installer reported that magnetic switches have a failure rate of less than 1% over 5 years, far lower than mechanical switches. Their small size (some are as small as 1 cm long) and low power consumption also make them ideal for battery-powered devices. For reliable, low-maintenance electrical switching, magnetic switches are a staple in modern technology.