by ericmark »
Sun Feb 17, 2008 5:59 pm
Regulation 442.2 does give formula to work out the distance between high voltage earths and low voltage earths but there are no regulations as to the distance between low voltage earths. We are after all only talking about 500ma max more likely 100ma which will only flow in fault conditions and in reality you both will have the same gas and water pipes so will be connected anyway. In days gone by before we had earth leakage trips on the whole of our supply there may have been a problem but not with todays earth leakage trips and the problem would not be tripping out your trip.
Your trip basically measures the power out on the live wire and the power returned on the neutral wire and if they nearly match within 100ma then trip will hold in. For you sockets you will have a second RCD with 30ma which works the same way.