Car Audio Power & Cable Sizing Tool
Sizes primary DC power wire and battery fuses for aftermarket sound systems. Distinguishes true RMS output from peak marketing claims and models real musical crest factors.
Enter the values above and click Calculate to view recommendations and engineering specifications.
The OFC vs CCA Danger in Car Audio
Calculation Assumptions
- Class D amplifiers operate at ~80% efficiency; Class AB amplifiers operate at ~50%–60% efficiency.
- Average continuous music draw is ~33% to 50% of amplifier peak RMS rating due to music crest factor.
Engineering Limitations
- Continuous competition sine-wave test tones draw full 100% current and require larger conductors.
A 1500W RMS Class D amp draws ~125A music continuous (150A peak). An 18-foot power cable run requires 1/0 AWG copper paired with a 150A ANL fuse near the battery.
Car audio wiring is uniquely vulnerable to marketing deception. Many budget amplifier wiring kits use Copper Clad Aluminum (CCA) wire instead of Oxygen-Free Copper (OFC):
- The CCA Resistance Penalty: Aluminum has roughly 60% higher electrical resistance than copper. A 4 AWG CCA cable behaves like a much thinner 7 AWG copper wire, causing severe voltage drops that trigger amplifier clipping, distorted bass, and thermal shutdown.
- Thermal Hazard: CCA wire oxidizes rapidly and becomes brittle under engine vibration. Always specify 100% OFC stranded copper for heavy automotive amplifiers.
- Main Fuse Placement: Install an inline ANL or Mini-ANL fuse within 12 to 18 inches of the positive battery post. This fuse protects your vehicle from burning to the ground if the power wire chafes through the firewall grommet.
Frequently Asked Questions
What size wire do I need for a 1000W or 2000W car audio amplifier?
For a 1000W RMS Class D amplifier (drawing ~90A at 13.8V with 80% efficiency) with a typical 15-foot run to the trunk, 4 AWG pure copper OFC wire is recommended. For a 2000W RMS amplifier (drawing ~180A), 1/0 AWG pure copper cable is required to prevent severe amplifier voltage clip and power loss.
What is the difference between OFC and CCA wire in car audio?
OFC (Oxygen-Free Copper) is pure copper with high electrical conductivity and corrosion resistance. CCA (Copper-Clad Aluminum) has an aluminum core coated in copper, which has 40% higher electrical resistance than pure copper. Using CCA requires jumping up 1 to 2 wire gauge sizes and poses severe terminal oxidation risks.
How do you calculate car audio amplifier current draw from RMS wattage?
Peak Current (Amps) = Total RMS Watts / (Operating Voltage * Amplifier Efficiency). Class D amplifiers typically achieve 75% to 85% efficiency, while Class A/B amplifiers achieve only 50% to 60% efficiency, generating substantially higher thermal current draw for identical acoustic power output.
What size fuse should be installed on a car audio main power wire?
The main inline power wire fuse must be rated to protect the cable itself: 100A-150A for 4 AWG OFC, and 250A-300A for 1/0 AWG OFC. The fuse should be installed within 18 inches of the positive battery terminal to prevent vehicle engine fires in the event of an accident.