jackrae:
Maybe a "repossessed" one from an industrial site/employer in the mistaken belief that they were enhancing their home safety. That said, the original poster did state the RCDs in question were 100mA and 300mA.
Central house RCD protection installed just after the electricity meter is rated at 300mA.
Individual mains outlet circuits are protected by 30mA RCDs.
The pool supply distribution board, which then supplies pool pumps, pool light, etc, is protected by 100mA RCD.