In this guide
The wiring kit is the least exciting part of an amplifier install and the one most likely to ruin it: undersized cable starves the amplifier, and a missing or wrongly placed fuse turns a fault into a fire. Here's what to buy and why.
Cable gauge: match it to the current
Amplifiers draw current, and thin cable can't deliver it — the symptoms are dimming lights, an amp that cuts out on bass peaks and a system that never sounds as strong as it should. Size the power and earth cable to the amplifier's total fuse rating and the length of the run: 8 AWG for small amps, 4 AWG for most systems (as in kits like the Connection FSK 700), and 0 AWG once you're into high-power or multi-amp territory. When in doubt, go thicker — oversized cable costs a little more and does no harm.
Fusing: the part that protects the car
A fuse close to the battery, usually within around 30cm, is not optional. It exists so that a cable shorting against bodywork blows a fuse instead of igniting. The amplifier's own onboard fuses protect the amplifier; this one protects everything else.
Earths, signal cable and noise
A poor earth causes more problems than any other single mistake: keep the earth run short, take it to bare, clean metal, and don't share it with other accessories. Run RCA signal cables down the opposite side of the car from the power cable — running them together is the classic cause of alternator whine. Where you're taking signal from a factory stereo without pre-outs, a line output converter such as the AudioControl LC2i does the job properly.
Buy the kit with the amp
It's the cheapest part of the install to get right and the most expensive to redo, because fixing it means pulling the trim and carpet back up. Our amplifier buying guide covers choosing the amp itself — tell us which one you're fitting and we'll spec the wiring to match.
Frequently asked questions
Can I use the cable that came in the box?
Amplifiers rarely include power cable. Kits bundled with cheap amps are often undersized — check the gauge against the amp's fuse rating rather than assuming.
What does AWG mean?
American Wire Gauge — the lower the number, the thicker the cable. 8 AWG suits modest amplifiers; 4 AWG is the sensible standard for most systems; 0 AWG is for high-power builds.
Why does the fuse go near the battery?
To protect the car, not the amplifier. A fuse within about 30cm of the battery means a chafed or shorted cable blows safely instead of becoming a fire.
Written by the CEN team in Nottingham — car audio installation specialists. Questions? Contact us or call 0115 924 0666.
