MC-38 Window/Door Magnetic Sensor (Normally Closed) is a very simple magnetic switch used in security and alarm systems to detect whether a door or window is open or closed. It’s sometimes called a reed switch or magnetic contact sensor.
Switch Type: Normally Closed (NC) — circuit closed when magnet is near, opens when magnet moves away.
Rated Voltage: Up to 100 VDC (some sellers list similar up to ~200 VDC)
Rated Current: Typically 0.3 – 0.5 A maximum switching current
Rated Power: Around 10 W (sensor itself only switches a signal, not heavy loads)
Contact Output: Reed switch with NC contact — closes circuit in presence of magnet
Actuation (Sensing) Distance: ~10 – 25 mm between magnet and sensor (varies by magnet strength and alignment)
Life/Cycling: Often rated for on the order of ≥1,000,000 operations (many thousands of cycles)
Housing Material: ABS plastic (simple surface mount)
Color: Usually white
Sensor Dimensions: ~27 × 14 × 7.5-8 mm (main body)
Magnet Dimensions: Similar compact size in matching part
Cable/Lead Wires: Pre-attached wires ~25–30 cm long (24–26 AWG)
Mounting: Adhesive tape or screws for surface installation