Many thanks all for the excellent suggestions, I have a way forwards now! I think I will look at using a phone charger for the 5v, replace the relays with an SSR and separate out the earth wiring all connected together at the source.
killzone_kid
To clear up any confusion our generators are connected in star configuration, this gives 3 phases of 230v and a common point which is neutural (earth at the generator). Your average house only recieves one of these phases through a 60A/80A fuse plus the 4th neutural wire, a third wire, local earth, is provided with a 3 foot metal spike in the ground. My house because it is large has two power supplies, both on the same phase to avoid lethal shocks. 115v isn't so dangerous (but can still kill you), 230v gives a nasty kick and can kill if you are unlucky, 415v which is the voltage across two phases is pretty lethal. see below for further explanation