Fan is on the same circuit for RCD. So, when testing my RCD all 3 things go off - fan, bathroom lights and kitchen boiler.
Also, fan and kitchen boiler are fused together - so i have a single fuse in my switch box that switches off kitchen boiler and bathroom fan.
Is it just me that thinks this first line reads as though the items are on separate MCB/fuses but on the same RCD? Definitely need some pictures?