Seem to have read something like this yesterday, maybe a different forum? I had not heard of Boilermate so looked it up, it has a PWM controlled pump, PWM stands for pulse width modulated, so it can use a higher frequency to standard 50 Hz, so may need type F RCD?
However first what is tripping?
Using RCBO's to use a dedicated one for the Boilermate should mean nothing else will affect it, a RCBO is a MCB and RCD combined, but with the MCB you get multi MCB's fed from one RCD, so adding another will not really help to stop RCD tripping.
We have three tools, the RCD tester
is used to see the RCD is doing what it should, the insulation tester
is used with the circuits dead to check for leaks, but it used DC so will not pick up leaks due to capacitive or inductive linking, so the clamp on
tests the circuit does not exceed 9 mA with a 30 mA RCD. It would seem likely the fault is a neutral earth fault, as with these the more power used, the greater the leakage, and the problem is some thing plugged in even if switched off can cause a earth - neutral fault, so bit of damp toast in the toaster can trip the RCD when the kettle is used.
However with the tools shown an electrician should quickly work out faults like that, so assuming the electrician both knows what he is doing and has the correct test equipment we must be looking at some thing unusual.
Which makes me wonder if the Boilermate needs a type F.
However I remember walking in on an "electrician" working in my late dad's house, and all he had was a multi-meter. So has the electrician actually tested correctly? If he has given the Boilermate it's own circuit but still coming from same RCD, one must question his skill, trial and error can work to an extent, but really we need the meters.
