I live in a rural area and had a heat pump installed 3 years ago which has been working perfectly. Since the recent rain, the heat pump started tripping the house RCD (30mA). The heat pump has its own separate 300mA RCD (which has never tripped) but shares a common earth with the house. There is an earth rod in the ground which has been there about 30 years. The 30mA RCD is new (I thought this was the problem - obviously not!)
If I switch the fuse box off in the house and remove all the fuses, the heat pump still trips the house RCD? The problem therfore cannot be with an appliance in the house. If I switch the heat pump off (isolate it) then switch the cooker on with all plates on maximum, it too trips the RCD. The problem cannot therefore be with the heat pump.
Is it an earthing problem? Has the recent rain washed away the soil surrounding the earth rod thus reducing its effectiveness. Should I install a new earth rod? Help!!!