VEHICLE WIRING
VEHICLE FUSING
For safety purposes, a high current fuse (or circuit breaker) MUST be installed in line with the amplifiers(s) immediately at the battery to prevent vehicle damage should the battery line in advertently shorted to the vehicle chassis. The chart at the right shows the recommended master fuse sizes for an average audio system with noted “rms” output power levels.
SYSTEM FUSE CHART
(Fuse size for total amplifier system power in “rms” watts)
| 100 W | 200 W | 500 W | 1000 W |
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Fuse Size | 20 A | 30 A | 50 A | 100 A |
(in amps) |
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POWER WIRING
Most vehicles built since 1990 have adequate current capability for your amplifier. Except for systems above about 500 W rms, the factory charging system and battery should easily support it if properly installed. Proper wire size must be chosen to ensure adequate current delivery to the amp. Wire size (gauge) of the cables need to increase in size for higher power systems. (Wire sizes larger than those noted are usually a waste of time and money since they offer Little or no performance improvements.)
Wire diameter must increase (decreased wire gauge number) for higher power systems. For long wire runs the wire diameter must also increase. The wire sizes noted allow for a maximum 0.5 volts DC drop over the give wire run which results in Sound Pressure Level drops inaudible to the average listener.
SYSTEM POWER AND GROUND WIRE CHART
(Wire gauge for total system in 'rms' watts)
WIRE LENGTH | 100 W | 200 W | 500 W | 1000 W |
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5 ft. / 1.5 m | 12 | 10 | 8 | 4 |
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10 ft. / 3.0 m | 12 | 10 | 8 | 4 |
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15 ft. / 4.5 m | 10 | 8 | 6 | 2 |
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20 ft. / 6.0 m | 10 | 8 | 6 | 2 |
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25 ft. / 7.5 m | 10 | 8 | 4 | 0 or 00 |
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SPEAKER WIRING
As with power wire, speaker wire size (gauge) changes with the power required and the length of the wire run. The speaker wire chart shows the minimum recommended wire size for a single audio output channel driving a loudspeaker at a given distance with a maximum power loss of 0.5 dB, the threshold of audibility. (Wire sizes larger than those noted are usually a waste of time and money since they offer little or no performance improvements.)
LOUDSPEAKER WIRE CHART
(Wire gauge per loudspeaker/speaker power in “rms” watts)
WIRE LENGTH | 20 W | 50 W | 100 W | 200 W |
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5 ft. / 1.5 m | 18 | 16 | 16 | 16 |
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10 ft. / 3.0 m | 18 | 16 | 16 | 16 |
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15 ft. / 4.5 m | 16 | 16 | 16 | 14 |
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20 ft. / 6.0 m | 16 | 16 | 16 | 14 |
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25 ft. / 7.5 m | 16 | 16 | 14 | 12 |
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FINAL VEHICLE WIRING
Current requirements for an upgraded audio system dictate a dedicated power line be run from the amplifier directly to the battery of the vehicle. This line should NOT be run to the fuse panel of the vehicle but directly to the battery. DO NOT run to the alternator either. There MUST be a fuse installed at the battery with adequate amperage as shown in the chart above.
As for the final signal wiring, be sure to route the audio cables down the side of the car opposite the power lines to avoid noise pick up from the lines. Also, try to route all audio cables away from noise sources such as engine computers and ABS brake computers.
Proper power grounding is important to insure adequate current flow. Be sure to grind the surface clean of all paint to ensure a solid electrical connection.
Battery
Fuse or
Circuit 
Breaker
Radio
Power Antenna
Speaker Wires
or
RCA Cables
Speakers
Amplifier
Ground Screw Drill 1/8” hole in chassis sheet metal
Battery
Connector
Grommet To prevent damage to power wire
Power Wire 
(10 gage
wire or larger)
Use the same ground if using multiple amplifiers
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