It can be seen that the building access control was burned.

There are many brands of visual access control, and the circuit design of each model is different, but usually there are at least five lines for access control: power supply (12V), ground wire, unlocking control line, telephone wire, video wire, and some have a separate video ground wire. If eight network cables are cut at the same time, it is possible to short-circuit the 12V power supply with other cables at the moment of cutting. 12V short circuit with ground wire will burn power fuse or cause power protection. If 12V is short-circuited with the call line or the unlock control line, the motherboard may be burned out.

At present, there are more and more intelligent devices in residential quarters. Do not cut and connect the original lines easily when decorating, which may cause some devices to fail to work normally or damage the intelligent management equipment.