Varistor between Live and (safety) Earth

[ppppenguin]

High earth leakage makes life difficult if you have to use an RCD. 6 items each leaking 5mA will certainly trip a 30mA RCD. In domestic installations all sockets must be protected with an RCD, there are a few exemptions but it's awkward to use them. Also most concealed wiring must be RCD protected which can make it difficult to fit a fixed appliance without RCD protection. The rules are different for commercial premises