Re: Where do you get "power" from for accessories ?
The number of accessories run willl determine the best way to wire everything.
For a single circuit, run a wire (stranded cable for all automotive applications) from the battery. Make sure there is a fuse as close to tbe battery as possible. Aquire a relay with a rating higher than the accessory being powered. Find a trigger circuit that you want to use (ie. key on engine off, key on engine on, marker lights, head lights, etc). Once you have all the wires run and determined the best place for the relay, make all connections as per wiring diagrams.
For multiple accessories using the same trigger circuit, use a mini fuse block. Some aftermarket units are available that have relays already installed with provisions for a few trigger methods. A heavier gauge wire will be needed from the battery to the fuse block and size is determined by the amount of current being drawn.
It should be noted that all accessories should have a relay to disconnect power to it until needed. Radios, alarms/security systems, power steps are a few exceptions that should be kept hot at all times, but most everything should be activated by turning the key.
2016 F-350, FX4, CCLB, 6.7PSD, 7" OUO/ICON/FOX lift, 38x13.50-18 Toyo MT