I have fitted underfloor heating, using a WarmUp Wifi thermostat.
When i turn it on, the RCD trips after 5 seconds on initial turn on.
I have measured the following;
Live - Neutral - 39 Ohm (expected for size of mats)
Neutral - GND - >1M
Live - GND - ~150k
Now the L-G resistance of 150k seems...