hi to all, although i've not posted for a while, i've been at the forum almost every day ! A question about 3 phase. I want to build an emergency light system for my woodwork shop ( it's on a farm where the 3 phase goes down quite often ) powered from 4 - 6 car batteries that will be charged from a wind turbine ( yet to be built). The question is , how can i detect when the mains power goes down without actually making a live connection ? My first thought was to wrap several turns of copper wire to form a coil, round the main incoming cable to try and get an induced (small) voltage that could be rectified and used to interface with an 'axe ? any comments or suggestions would be appreciated.