OP
Engineer54
Fortunately or unfortunately, i prefer to live in the real world rather than what BS7671 says!! On a UK TT system, If you lose the 30mA RCD operation for any unforeseen reason, that's your installations (or part of) earth fault protection gone!! There is nothing additional about them, only good while they are working....
In the vast majority of UK TT situations, the up-front 100/300 mA S type won't exist!!
In the vast majority of UK TT situations, the up-front 100/300 mA S type won't exist!!