The large terminal at the top gets the battery cable from the positive (+) post, and a smaller wire (8 or 10 gauge) is also attached to the top terminal which supplies battery voltage to the ignition switch, ammeter, and/or the vehicle's fuse block. The "S" terminal gets the wire from the ignition switch "start" position. The "P" (sometimes labeled "I") terminal is used to supply full battery voltage to the coil of a point-type ignition coil during engine start. If you have a HEI ignition system, nothing is attached to that wire.

You probably don't need a support bracket, but if you want one, simply make it out of 1" wide 1/8" thick flat steel stock.

It would help to know what vehicle you're working with and if it's got an original equipment wiring harness.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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