Proper fusing of a car audio system
 

    Although it may seem like a trivial thing, proper fusing of a car audio system is often overlooked or done improperly. In either of these circumstances, the installer is putting the system's owner (usually himself) at risk of injury or possibly even death. This article will try to outline proper fusing techniques in the hopes that at least one person won't burn their ride to the ground accidentally.

    The first thing to do is to buy a fuse holder or fuse block (everybody makes these, from Radio Shack to Street Wires to Phoenix Gold). If you have multiple amplifiers, you may wish to pick up additional fuse blocks, or even a fused distribution block.

Next, we should find out how large of a fuse we should need. The purpose of the fuse is NOT to protect the amplifier. Amplifiers have internal fuses for that. Rather, the fuse is to protect the car, the power wire itself, and the battery. In a short, the wire would begin heating up, causing the insulation (and anything nearby) to burn or smolder. With very large gauges of wire, it is possible that, without proper fusing, the battery could burst (and because batteries give off hydrogen gas when discharging, an explosion is perfectly possible). For the main wire, you can do this in two ways. The first way, if you have a high power system, is to simply select a fuse which is equal to 1/2 of your power wires maximum current carrying ability. For most systems, however, the power wire will carry much more current than the system will ever need. It is more practical to base the fuse size on the actual amount of current draw. What you don't want to do is add up the size of the fuses on each amplifier. That is not at all representative of the potential current draw. Take the output wattage of your amplifiers, and double that number (this assumes that most amps are at least 50% efficient, although that is not a hard rule). Then, divide by your system voltage (14.4 volts). This number is the amount of current your system will draw under maximum loading. Add about 20%, and then select the closest fuse size. If you occasionally blow a fuse, it's okay to move up a few amps, but if they blow frequently, check your connections.

by: Matt Walters