Electrical wiring is usually something that is thrown by the wayside when outfitting your vehicles with accessories. There are few people who enjoy the process of designing their own looms, and taking the time to run them and make them look neat.
Most often, wiring becomes and afterthought and becomes a hodgepodge of miscellaneous wires, relays and butt connectors that ultimately end up as a rat’s nest and have no business being there.
But even people that do care about how their wiring looks, often overlook the performance ratings of wire itself. When needing to supply electricity over a distance, wire gauge must be considered to ensure that enough electricity can flow to safely supply the accessory however far away it is. As distance increases, so does resistance and in order to flow the needed electricity, gauge must be increased.
This helpful chart below from Waytek Wire shows the different amperages that wires can handle, and the maximum lengths for those gauges and amperages on a common 12v DC system that all commercial and consumer vehicles use.
For those of you who rock a former military vehicle that uses a 24v system, this chart is not applicable to you, but a simple google search can net you the answers you are looking for.