Example bases are described. One example base includes an insulating housing, where the insulating housing has a first surface and a second surface that are away from each other. The first surface is configured for a detachable connection of a circuit breaker. The second surface is provided with a first mounting slot. The insulation housing can be slidably snapped into a mounting rail in power distribution equipment by using the first mounting slot. An accommodating cavity is provided in the insulation housing. The accommodating cavity is configured to accommodate a conductive connection member. One end of the accommodating cavity is open along a sliding direction of the insulating housing relative to the mounting rail, and the other end thereof is closed. The base is used to install the circuit breaker.