When the secondary output of the isolation transformer is connected to the switching power supply, does the input of the switching power supply need to be grounded?

The isolation transformer is a mutual inductance transformer with a turn ratio of 1 to 1. Because the primary and secondary are separated, there is no direct connection of electricity, and the human body will not get an electric shock if it touches any wire of the transformer twice alone (the human body will get an electric shock if it touches two wires of the transformer at the same time). Suitable for home appliance maintenance personnel. When an isolation transformer is used to supply power to the switching power supply, the input end of the switching power supply cannot be grounded, because after grounding, when people accidentally touch the non-grounding wire of the transformer, the current will be introduced into the earth through the human body and form a loop with the grounding wire to get an electric shock, thus losing the safety isolation function of the isolation transformer.