Buy a set of radio control adaptors, the things for turning stuff on and off remotely. Buy a resistor of about 5 k?, 10W and wire it into a plug from live to earth. Put the plug into the remote control adaptor and get it plugged into a socket in his house, out of sight. When you want to shut him up, turn on the remote control adaptor. The current will trip his ELCB. The remote control adaptor will reset to the off position so he can get everything started again, but that also makes it almost impossible to trace your addition. You can test it all out in your house.
Robert-Jan