[McMurdo]

if you mount the socket conventionally you might want to think about if you want the earth on the socket to be connected electrically to the case of the transformer or not, as it will be via the mounting screws.

My transformer uses an all-insulated box and the screws and socket earth are isolated completely from the incoming mains earth.

Filtering on the appliance under test may otherwise cause parts in it to acquire a high floating voltage by referencing it to mains earth.