I am fitting an extractor fan, with an led light and vented with an inline fan that dumps through the soffit. It requires a circuit breaker with a 3mm gap. My question is: does this relate to the RCD in the consumer unit or its it simply meaning that it needs to be connected via a switched spur with the switch having a 3mm gap? If the latter, can anyone recommend such a switch as I don't remember seeing measurements like this on the spurs I have used previously. I was intending to take the power for the fan from the same circuit as the shower itself, but before the shower isolation switch. I really appreciate any advice that can be offered.