Disclosure: This article contains affiliate links. As an Amazon Associate I earn from qualifying purchases, at no extra cost to you. Door and window sensors are the cheapest, most useful part of a wireless alarm: a small sensor on the frame and a magnet on the moving part. When the magnet moves away, the sensor tells the hub. Installing them takes minutes, but alignment and gap matter more than most people expect. This guide covers where they go, how to mount them and how to test them. It is part of our DIY home security setup guide , and sensors explained covers how each type works. Where to put them Sensor on the frame, magnet on the moving part. Abode's and Alarm Grid's guides both say to fix the sensor to the door or window frame and the magnet to the door or window. Reverse them if needed. Abode says that where the frame protrudes beyond the door, the magnet may need to go on the frame and the sensor on the door. Cove says the same for narrow window frames. Sliding...
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