There are provided a device for preventing an entire cabinet from being powered down, a cabinet, and a method for preventing an entire cabinet from being powered down. The device includes a diode and a first protection circuit. An anode of the diode is grounded, a cathode of the diode is connected to an external voltage supplying copper busbar via the first protection circuit, and the diode is connected in parallel with an external node. The first protection circuit is arranged to monitor a current flowing through the diode, and cut off a connection line between the diode and the voltage supplying copper busbar in a case that the current exceeds a preset fusing current threshold.