Isolator switch for SELV extractor fan

[webde]

The manufacturer says that I should fit a double pole isolator spur before the pullcord switch/light switch. This will be very difficult because of access. Can I instead insert a three pole isolator immediately before the transformer?

Also, could I incorporate two RCD devices in the permanent live and switched live as the main supply to the house has no RCD on the consumer unit and the existing mains operated fan comes off the bedroom lighting circuit.

 

[ban-all-sheds]

The manufacturer says that I should fit a double pole isolator spur before the pullcord switch/light switch. This will be very difficult because of access. Can I instead insert a three pole isolator immediately before the transformer?

Putting it before would mean it also isolates the light. A 3-pole isolator between switch and transformer is what you need.

Also, could I incorporate two RCD devices in the permanent live and switched live

No - they'll always be seeing an imbalance, and will trip. You need to put an RCD into the lighting circuit before the bathroom. But even that isn't a perfect solution.

as the main supply to the house has no RCD on the consumer unit

I would advise rectifying that.