Starter/electrical clicks one time and then nothing works, lights, dash lights, etc?

When I turn the ignition switch, sometimes the solenoid clicks one time, and then nothing works, lights, dash lights, etc. I have a new Optima battery and new battery cable. I have check the volts/ground from the battery to the bus block/junction box on the firewall and on the fusible links. I have also check two of the red wires where the wiring web enters the firewall next to the steering column. I am getting good voltage up to that point. I'm not sure where to go from here: ignition switch? What would cause so much draw?