Topic: Car Audio Wiring

What is the one part of a car audio system that you absolutely cannot do without, or skimp on? Wiring. The best way to think of car audio wire is to think of it as the veins of an audio system. Wire will deliver amperage which your amplifiers are hungry for, wire also drives wattage to your subs and speakers. Wire is divided in different sizes we know as gauges which is used as the standard rating system. The lower the number gauge, the thicker the wire. Lower gauge wire is normally used for grounds, amplifiers, and subwoofers. Higher gauge wire is generally used for speakers, tweeters, crossovers or other small applications. We will look at some common terms that you come across when looking at wire.

The first term is AWG which stands for American Wire Gauge Standard which is a standardized wiring system used in the United States to determine the thickness and capabilities of wire. This term is important to pay attention to since some brands of wire ignore this system. For instance if a manufacturer does not use the AWG system then it is possible that wire with a “4 gauge” jacket only has 8 gauge of actual wire inside. The common sizes of wire found in car audio for amplifiers are 3/0, 1/0, 2, 4 and 8 gauge, these are considered power wire and are single conductor (either positive or negative, but not both). For subwoofers and speakers you will find dual conductor (carries and positive and negative polarity) in the following sizes 10, 12, 14, 16, 18 and 22 gauges. There are many other ratings however these are the most common sizes you will see in car stereo applications.

Next is OFC which is short for Oxygen Free Copper which helps determine how well the copper conducts electricity. This is of course especially important in car audio application to ensure the amplifier or speaker is receiving the absolute maximum amount of energy transfer possible. Some wire manufacturers will also include a very small amount of tin in the wire which helps reduce the chance of corrosion over a long period of time. This is important for applications where the wire may be exposed to the elements such as inside an engine bay, or in a marine audio system.

The last term we will look at is Strand Count. This number will specify how many individual stands are braided together to create a single conductor. There are several advantages to individual stands over a single solid wire. The first is flexibility, it is much easier to install multiple strand wire since it can be bent and curved in any desired shape, whereas solid wire is almost impossible to bend at any angle. The second advantage is durability. Since there are many multiple strands even if a single strand were to break there is almost no loss in power transmission. In solid wire if a single strand is damaged power handling can be greatly reduced.

When it comes to actually choosing which gauge wire you will need for a specific application we recommend first determining the amount of current that will be flowing though the wire. We have included an wire gauge chart below to help you decide which gauge wire you will need. There is no disadvantage to using a larger gauge wire than you need so you are better off rounding up, rather than down. However, if too small of wire is chosen then it is possible for the wire jacket to actually melt due to too much current trying to flow though the wire. So an example using the chart below: if you were running a 1200 watt amplifier that is rated at 100 amps, and used 18 total feet of wire from the battery to the amp you would want to use 1/0 gauge wire. For longer distances it is possible to run a 3/0 gauge wire which can handle the 100 amp load for 42 total feet. This same rule applies for running multiple amplifiers, however first you need to add the total amperages of both amps together. So if you had two amps rated at 50 amps each you could still use 1/0 gauge wire if running less than 28 total feet.

So how do we determine the amplifier current load if we only know the wattage rating? Well there is a simple formula that can be used. If you have an amplifier that is rated at 1400 peak watts you would take that number and divide it by the voltage. From experience we recommend taking the most common voltage a vehicle will be operating at when running with the alternator turning which is about 14.4 volts. In other words this would be absolute best case scenario to allow the amp to draw maximum amperage. So we take our 1400 watts and divide it by 14.4 volts which give us an amperage rating of 97.2 amps. Once you have the number of total amperage between one or multiple amplifiers and the distance you anticipate the power wire will be (From the battery to the amp(s)) lets say 20 feet, you can now determine which gauge wire suits you best. So using our example (20 feet, 97.2 amps) we know by the wiring gauge chart below that you would need to use 1/0 gauge wire.

That covers power wire for our amplifiers; however there is also the ground wire we need to worry about. This is equally as important as the amp power wire. We recommend using the same size ground wire as you used for the power wire. Since DC (Direct Current) flows between positive and negative it is important to use the same size wiring to handle the load. Let’s take a better look at a ground wire. So you would want to ground your amplifier at the rear using the example amp above with a 1/0 gauge wire. Now the important factor to consider that is often OVERLOOKED is the factory ground to the negative battery terminal. Remember when you ground an amplifier at the vehicle chassis in the rear, the vehicle frame then becomes the transportation source for the negative electrical energy. Here’s the problem: near the front of the vehicle, usually near the firewall is another chassis ground that connects from the frame of the vehicle to the negative side of the battery (Factory Chassis Ground). Now why is this a problem? Factory grounds are NOT designed to handle the loads of your new high powered system. The factory ground is designed to handle the electrical load of the vehicle when it was purchased with the included electrical system load from the factory. So if your vehicle only has a 10 gauge factory ground and you are running a 1/0 gauge power wire your system will only be limited to handle the amperage rating of the 10 gauge factory wire:

This is why it is critical to remember to upgrade the factory ground at the firewall to the same size ground that is being used in the rear of the vehicle at the amplifier. The new ground wire can be connected to either the factory battery terminal or at an upgraded aftermarket terminal as pictured below.

Factory Chassis Ground	Wire Comparison
Upgraded Factory Ground	Upgraded Ground With Terminal
Click on pictures above to enlarge.

The method for figuring out what gauge wire to use with subwoofers and speakers is the same process as amps. You take the total wattage of each speaker / sub and divide it by the voltage to calculate the amperage rating. Then from there use the gauge wire chart below to determine what gauge wire you will need to use. Speaker wire is dual conductor wires which will mean one lead carries positive and the other carries negative.

Gauge Wire Chart