A friend asked me what he should look out for if he agrees to allow a new communal CCTV system to be powered from his home supply. I wonder if any of you more expert than I has any wisdom to pass on?
The CCTV system is to be installed on a shared piece of land owned by the surrounding residents and needs power. One option that the installer says is frequently used is to take off a feed from the domestic ring of the nearest house, via a meter to measure how much power has been used so that the kind resident isn't out of pocket. In principle, if properly installed, it sounds OK and a pragmatic solution.
However, I wonder if that might be storing up trouble because any earth leakage in this spur could trip the RCD of the main house circuit and be a pain to fix. Outdoor cable length might be up to 50m depending on routing. (How deep should it be buried by the way?) The power requirement is not likely to be more that a couple of hundred Watts, so I don't think voltage drop is a concern. A more difficult installation could take a feed from a separate MCB on the consumer unit, but the cable run would be longer and more disruptive than making a hole in the nearest wall as proposed.
I wondered about the merits of inserting a back to back isolating transformer as the supply leaves the house - any thoughts on that?
