Car Audio, Custom Fabrication, Mobile Electronics

How-To Choose The Proper Wire

Introduction

            In this blog we will go into depth on what to look for when purchasing the right wire for your car audio system. We will review the important properties and characteristics of power and speaker wire commonly used in car audio. We will cover subjects like; cross sectional area, temperature, conductivity and length of the wire. Make sure to pay attention to the graphs, pictures, videos and the below descriptions to get the most out of the blog!

WiresA collection of many different types of wire to compare and contrast.

The Difference in Materials

“Energy is neither created nor destroyed it is simply transferred.”

           When it comes to conductivity, an important characteristic to look at is the material of the wire. Silver is the highest standard of conductivity when it comes to natural metals but is almost never found in car audio applications. The most commonly found types of wire in car audio are Oxygen Free Copper (OFC) and Copper Clad Aluminum. In this section we will cover the advantages and disadvantages of each type or wire.

LIS Audio “How-To Choose Wire” – Wire Materials Part 1

Copper Clad Aluminum (CCA) – Commonly abbreviated, as CCAW or CCA, is an electrical conductor composed of an inner aluminum core and outer copper cladding. The conductivity of CCA is 63% efficient to silver.

Oxygen Free Copper (OFC) – Oxygen-free high thermal conductivity (OFHC) copper is a group of wrought high conductivity copper alloys that have been electrolytically refined to reduce the level of oxygen to .001% or below. This is the most commonly used and most reliable type of wire in car audio, as opposed to Copper Clad Aluminum (CCA). OFC is 97.6% conductive to silver.

CorHere is a picture that shows what a corroding battery terminal looks like with oxidization.

         Having the right electrically conductive material is important when it comes to moving current efficiently. OFC is much more conductive than CCA which makes it a better choice for car audio applications. CCA is known to oxidize and corrode when it is exposed to the elements. This is not the case for OFC. Gold is 76.6% conductive to silver but holds up to the elements much better than most metals, which is why it is commonly used to plate terminals and connectors but not found in wire.

S vs OThe wire on the right is much more rigid due to the low strand count of copper.

            Avoid using solid core wire, or wire with a low strand count, because the wire being in a high vibration environment may easily back out of its originally secured location. Daily driven vehicles, boats and UTV’s are considered high vibration environments. Wire with higher strand counts tend to be much more flexible in reference to installation and exposure to regular vibration. The material chosen can also effect how easy or hard the wire is to install.

CCA vs OFCThe wire to the left is OFC and the wire on the right is CCA, both rated 00 AWG.

The Importance of Wire Size 

          The size of the wire is extremely important when trying to figure out the maximum amount of current it is capable of delivering. Similar to a pipe moving water or a line moving air, the larger around it is the more mass it can move though it. With wire it’s about transferring electrons and ions from one point to the next. So, the larger the gauge wire, the easier it is to move the electricity.

LIS Audio “How-To Choose Wire” – Wire Size Part 2

            Wire size, is gauged by how much surface area or cross sectional (thickness) area that the wire offers. The length of the wire is almost as important as the cross sectional area. Knowing how long your wire needs to be in combination with knowing how large the diameter should be is important when figuring out how much power can be transferred efficiently. Of course you will want to keep the material it is made from in consideration here as well.

The chart below acts as a quick reference guide for wire size and length:

LIS Wire Gauge Chart           

            This chart is accurate to Oxygen Free Copper wire. When it comes to using Copper Clad Aluminum over OFC use wire one size above what is recommended here in the above chart. Even though it is not recommended to use CCA due to the fact that the integrity of the wire is compromised when exposed to the elements. It is possible to use it if there is no other option, or if the budget does not allow for OFC wire.

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           An easy and accurate way to quickly determine what size of wire may be used at bare minimum for an application is to add together all the amperage ratings of the fuses for the amplifiers. The onboard fuses tell us how much current the amplifier is capable of drawing which indirectly translates into how much power it is capable of delivering. For example, if there are two amplifiers each having two 40 Amp fuses on board, the total current draw would be something around 160 Amps or approximately 2,304 Watts of power. We will review this in more detail, and the math behind it, in a later section.

AmpsAn example of two amplifiers each with two 80 Amp fuses and the proper OFC wire size for the setup.

Wire Temperature & Jacketing

         The temperature of the wire is important due to the fact that power wire and ground wire can often be exposed not only to the outside elements but also to the engine bay, which can have very high temperatures. I will describe in the video below some of the disadvantages of wire that cannot handle the average temperatures that may be encountered when installing wire into a vehicle.

LIS Audio “How-To Choose Wire” – Wire Jacket & Temp Part 3

         In high output situations, electronics and wire can get very hot due to the high level of current and the amount of resistance in the wire. Keep in mind that copper is not only a great conductor of electricity but also a great conductor of heat. Heat can easily transfer from one component to the next if the system is not set up and regulated properly.

105C

         When it comes to the temperature of the wire, the jacketing and the copper both have different melting points. Overall, using wire that isn’t affected from 221 degrees Fahrenheit (105 C) and above is important. The melting point of the copper in the wire is much higher than the melting point of the outer jacketing but if the wire gets hot enough the integrity of the copper can begin to break down and become much less conductive.

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       The jacket of a wire can be made of latex, polymers, PVC, a combination of rubbers or even thermoplastics. The main functions of the outer wires jacket are to protect the wire from outside elements and to reduce the chances of it being pierced. Some jacketing is very rigid and hard to bend while others are almost “gummy” in nature and extremely easy to bend. The flexibility of the jacketing is important when it comes to routing the wire through an entire vehicle.

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Wire Connections

         There are recommended ways of making wire connections, and then there are the wrong ways, which of course are not recommended. The 4 most popular wire connections that are NOT recommended are with the use of T-Taps, Scotch Locks, Wire Nuts, and Crimp Caps. These methods are not recommended due to the fact that they are not strong conductive connections, may compromise the integrity of the circuit or may not hold up in a high vibration environment, like a vehicle.

20190310_161659_20190426051319594_20190428063202609This picture shows an example of how not to extend or connect large gauge wires.

        The best thing you can use to make wire connections is solder. Soldering is the best possible option for connecting wires because it creates a mechanical bond between 2 pieces of wire (similar to a weld) and the solder creates a protective shield around the wire connection that keeps out oxygen and moisture to prevent corrosion. Solder is best used for connections not exposed to sources of heat that produce more than 221 degrees Fahrenheit (105 degrees Celsius).

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     The next best connections are distribution blocks, terminals or fuse holders. Especially when it comes to large gauge wire and larger amounts of power. Using these parts to connect wire will allow for a solid connection with little to no chances of voltage drops through the circuit or corrosion. The use of terminals, lugs or solder, to connect to any number of parts offered for wire connections, maybe necessary to ensure solid contact and prevent unexpected detachment. Soldering large gauge high current wire that may produce high levels of heat is not recommended.

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     When choosing connectors, battery terminals, wire reducers, fuse holders and distribution blocks it is vital to pay attention to the material they are made from. Most commonly found cost effective of the parts listed above will be made from brass, stainless steel, nickel and aluminum as to assure they endure the elements. Where higher end connectors will be made of copper. This is obviously due to the fact that copper is a much more efficient conductor than the other materials listed.

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       Some of these connectors and terminals will be constructed of one material and plated with a more efficient and less corrosive material, such as brass plated in gold. Make sure to read the descriptions of the parts, and try not to identify the material just by their images. For the best current flow use the most conductive material. The chart below shows the overall conductivity of the materials mentioned for connectors.

Cond Chart
The chart to the left shows the conductivity of different materials. To the right this depicts the sizes necessary to conduct an equilient amount of electric for each material.

          When it comes to reducing wire size from a power source to the load (i.e. alternator to battery, or battery to amplifier) distribution blocks are recommended. It is never recommended to use smaller wire to distribute to power sources that require larger gauge wire than what is coming into the distribution block. We will discuss much more on wire connections and how to properly perform these installations in a future blog on basic wiring techniques. So make sure you follow along!

DistroA small fuse block showing a 4 Gauge to dual 8 Gauge wire split between two amplifiers.

Touching On Grounds

        Using single point grounds, or source grounds, in the installation is the best way to alleviate any problems associated with ground paths. This can also make troubleshooting easier because the issue will arise within the entire audio system at once through the similar ground, or not. When finding a good ground point it is recommended that you avoid sharing the audio systems ground points with any factory electrical ground points. This will reduce the chances of unnecessary “clicks” and “pops” in the system.

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      When adding a new ground point be sure to sand or scuff the ground point to  remove the paint and primer which will ensure the best flow of electricity through the circuit. Many of the vehicles on the road today are constructed of different materials and designed many different was. Some vehicle, such as older late model cars, will have a solid steel frame that the body sits on. This frame acts as a lager conductor from front to rear as it is usually grounded to the front batter and motor. Utilizing the steel frame and body of an older vehicle is typically enough return path for most daily driven systems.         

WeldThis picture shows two sheet metal panels bonded together at the rear of a vehicle.

         When it comes to newer vehicles on the road we have variables we must consider that weren’t as prominent with earlier vehicles, such as, non-conductive bushings that may connect the motor or body to the chassis. With uni-body vehicles we have to consider the fact that the only conductive surfaces from front to rear are multiple pieces of sheet metal that is only connected by small spot welds and non-conductive permanent bonding agents.

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         Some manufacturers are even known to use materials other than metal to construct the vehicle leaving even less conductive ground return path. In some vehicles it may be necessary to run a full length ground along with the power wire, which is similar to marine applications. You can use all the same principals for finding the proper power wire material and length to determine whether, your vehicle specifically, has enough conductive surface area between the battery and audio system components in order to remain efficient.

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Marine & Luxury Craft Wire

        When it comes to marine audio installation it is important to extend the same amount of ground wire as positive to any powered source. Most marine crafts (boats, pontoons, floating homes, etc) do not have an abundant ground source throughout the entire vessel. Use the same or greater sized wire (within 19ft, or up a size if longer) to provide solid ground connection to the batteries and charging system. Do not rely on aluminum structures to conduct the proper amount of electricity.

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            It’s a bit of a different game when it comes to wiring up a UTV, motorcycle, scooter or any other small engine craft that has a stator in place of an alternator. Energy is neither created nor destroyed it is simply transferred. With this being said we recognize that smaller motors don’t create as much power as a full size vehicle engine and this translates in the electrical rectification process. Also having a smaller battery for electrical storage is another downfall to adding more “load” to a small engine craft. Make sure you know how much power can be added before choosing your audio system and wire to install it!

UTVUTVs may typically require high current wires that aren’t any larger than 8 gauge to run the full audio system due to the low powered electrical system.

Simple Science & Methodical Math

            If you’re familiar with Ohms Law this section can greatly benefit you for finding any number of ratings when it comes to Power, Current, Voltage and Resistance. If this is new to you then I will include a small definition and example to help you, some what, grasp the concept.

Ohm’s Law – Current in a circuit is directly proportional to the voltage, and inversely proportional to resistance. It also includes the relationships of watts to amps, volts and ohms. It is simply referred to as, the relationship of voltage, current and resistance. Now, lets go over the math and science to it all…

PIE

            Below is a wheel chart that is traditionally associated with Ohm’s Law and it directly shows the combinations of equations used to factor Power, Current, Voltage and Resistance. Underneath the chart you will find the equations written out to give you an idea of how the chart sections correlate with each other. First, lets start with the definitions of each of these four words.

Current (I) – The rate of flow of electricity, measured in amperes (amps). Often called Electrical Current.

Power (P) – The time rate at which work is done or the rate at which energy is used. This is typically measured in watts in 12 volt electronics.

Resistance (R) – Also referred to as Electrical Resistance (impedance), it is the opposition of current flow.

Voltage (E) – The electrical pressure required to do electrical work. Voltage is also caked potential. Voltage must be present for electrical current to flow within a closed circuit.

Screenshot_2019-02-05-08-21-52-2

The Ohm’s Law wheel chart makes it easy to find what equation may be necessary to find a rating.

            This chart below helps make it a bit more simple with it comes to using the equations in a real world scenario. Simply take measurements using the proper tools and plug in the numbers what they are needed to factor what it is you would like to know. Read them as it is setup to know when it is necessary to use each equation; If you want to find (Power)… And you know (Voltage)… Then the math is (Current) X (Voltage) = (Power)…

If you want to find… And you know… Then the math is…
Current (I) Resistance (R) and Voltage (E) E / R = I
Current (I) Power (P) and Voltage (E) P / E = I
Current (I) Power (P) and Resistance (R) (Sq.Rt.) of P / R = I
Voltage (E) Power (P) and Resistance (R) (Sq.Rt.) of P * R = E
Voltage (E) Current (I) and Resistance (R) I * R = E
Voltage (E) Current (I) and Power (P) P / I = E
Resistance (R) Current (I) and Voltage (E) E / I = R
Resistance (R) Current (I) and Power (P) P / I^2 = R
Resistance (R) Voltage (E) and Power (P) E^2 / = R
Power (P) Current (I) and Voltage (E) E * I = P
Power (P) Current (I) and Resistance (R) R * I^2 = P
Power (P) Resistance (R) and Voltage (E) E^2 * R = P

            From here it’s about knowing which tools to use and how to use them properly to test your audio system. This will allow you to figure the correct figures when it comes to your system. The tools needed to measure ratings, at bare minimum, are a Digital Multi-meter, Hall-Effect clamp (clamp meter) and an Oscilloscope. Stay tuned to our blogs as we will have a future write up sharing with you how to properly use these tools where we will show the real word difference between OFC and CCA wire.

Wire Installation Tips & Tricks

          When it comes to routing wire through the vehicle be sure to stay away from moving or rotating parts. Make sure the wire is secure without too much slack. Avoid securing the wire to the exhaust pips, drivetrain components (driveshaft, transaxles), the suspension components and  any gaps that might expand or contract when the vehicle is in motion. Also, be sure to use the proper zip ties or brackets to mount the wire when running through or outside the vehicle.

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       If the wire passes through sheet metal make sure there is a rubber or plastic grommet round the wire where it passes thought the metal to prevent a short. You may use rubber butyl or silicone caulk to plug the hole and secure the wire but its is not the most ideal method for preventing a wire short. If the wire is going to be exposed to the outside elements make sure that it is covered in a some sort of shielding. We typically will use techflex, wire loom or even a quality electrical tape.

WrongThis is a good example of a completely unprotected and improperly run power wire through a factory chassis hole.

         When running signal wires be sure to stay away from any possible high current wiring. Avoid fuse boxes and modules when running signal wire, and its is always a good idea to run the audio system power wire and signal wires on the opposite sides of the vehicle to keep them well separated. Running signal wires near high current wires or power source can cause interference such as fluctuating engine whine, pops or clicks.

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          Even if you don’t plan to perform the installation yourself hopefully this gives you a good idea what to look for in a quality installation. If you do plan to perform the installation yourself, make sure you take your time and use common since. My last installation tip would have to be, listen to music while your work!! Most of all, try to have fun!

In Conclusion

          Hopefully now you have a much better understanding of wire materials, length, size and safe operating temperatures. We have reviewed basic installation principals when it comes to measuring and gauging the right size and type of wire. We went over the disadvantages to heat and resistance in wire and through the audio system. We talked about the advantages of flexible jacketing and high strand wire when it comes t ease and durability of the installation. Now get out there and find some wire!!

20190125_122417A picture of the amplifier rack in a 1970 Dodge Charger we did. Properly wired, secured and separated.

          Feel free to leave comments or questions about this blog below! Any input you have that can be added will only help to educate others with a simple read, which is all I hope to achieve here! I hope you’ve enjoyed this read and please check out our blog for more information on other car audio related subjects!!

All pictures and videos are provided courtesy of LIS Audio of Kansas City.

Blog References & Sources:

LIS Audio Dictionary – www.lisaudio.com/dictionary

Basic Car Audio Electronics – www.bcae1.com

MECP Advanced Study Guide – www.mecp.com

Mobile Electronics Magazine – www.me-mag.com

LIS Audio YouTube – www.youtube.com/lisaudio

Wikipedia – www.wikipedia.org

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