Originally Posted by Soundwiz
........... I am going to put a 30 amp fuse on the control side of the solenoids, and upgrade the control wire gauge to AWG 8. that sould be enough to keep the voltage loss to a minimum.
While there's no harm in using larger wire than necessary, I wouldn't use a 30 amp fuse in this circuit. I've posted many times that the fuse is there to protect the circuit
, not the device, but in some cases, it protects both.
Suppose the solenoid has a maximum current draw of five amps and something happens to the solenoid where it doesn't engage. With thirty amps at twelve volts available, it may overheat and possibly catch fire.
Look for a label on the solenoid, contact the manufacturer, match it to one in a catalog that shows the current consumption, or just measure the current that flows through it when it is operated. Let's say the current is five amps. Your fuse should be 7.5 amps or 10 amps, no more. The wire can still have a larger capacity, that's fine.
As for voltage drop and operating at a lower voltage than designed for, you want a good, solid operation of the solenoid so the switch contacts are firmly engaged. Anything less and they may chatter, arc, and burn to where the solenoid must be replaced.