hi guys.. we are modifing fence lighting around the plant around 7 kms, power supply is like this, transformer(4160/480v - 75kva) to distribution panel(MCCB - 40A) to local control panel(we are using contactor to control the supply).. in local control panel there is H-O-A switch, we are using photocell for controlling in auto mode..there is total of six control panel and one master control panel..the same H-O-A is in master control panel.. we are taking cables from the local control panel to master control panel(nearly 3000 meters), we are using AWG # 14(7 core x 2.5mm2).. my doubt is how we make control from the master control panel.. if we make supply from the master to local control panel how much voltage drop it is?