I had a conversation with my old business partner -and I mentioned we had just installed a Daikin inverter that had tripped the consumer unit. He said "I bet it has a rcd"

http://www.memonline.com/rcd1.html

On gaining entry it did indeed triped the rcd. He mentioned that inverters communicate down the earth so there is an imbalance hence the trip.

I re-wired it to the other side of the consumer board (a split board) and every thing ran fine and dandy.

Now this seems to confirm the advice but I welcome any additional imput

Cheers

Richard