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Just changing the fuse to a 15 amp is asking for trouble. On my 09 the horn wire was 20ga at most. Use a relay and be safe.

Here is a wire chart I found and posted before. Happy to share it again.

http://www.offroaders.com/technical/12-volt-wiring-tech-gauge-to-amps/

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There are wiring kits you can get for this that help - Wolo makes them too - and they include a fuse.

You were right to be cautious about the car wiring, they make the wires just big enough to carry the expected current now - weight and cost savings supposedly - so don't overload them.

I prefer not to add another relay and do extra wiring.

The referenced wiring chart (“12 Volt Wiring Gauge Requirements at specific Amps for Automotive Electrical Systems”) indicates that a ten-foot length of 18 AWG wire can safely (?) carry 15 amps at 12 volts. The size of the wire from the relay to the OEM horn is probably 18 AWG and measures between three and six feet, surely no longer than six. So, it should be able to handle up to a 15-amp draw with “normal” usage, that is, for short blasts – not laying on the horn button for minutes.

But using an “Automotive Wire Size Calculator” (http://www.gtsparkplugs.com/WireSizeCalc.html) I determined:

(a) 18 AWG wire no longer than 4.32 feet should be used to carry 10 amps at 13.8 volts (2% voltage drop).

(b) 18 AWG wire no longer than 2.88 feet should be used to carry 15 amps at 13.8 volts (2% voltage drop).

A tech representative at Wolo Horns told me that with “normal” usage each of the two horns draw about four amps, total of about 8 amps. Nevertheless, he said I should use a 15-amp fuse with the set of Wolo Maxi Sound horns. But if normal use draws 8 amps, I guess it would be OK to use the 10-amp fuse. If I stick with the OEM 10-amp fuse, will it decrease delivery of the full potential to the horns?

I want the full potential but I don’t want to burn up wires. If I am wrong, I need to hear about it.

Thanks for help.

10 amp fuse will not limit the horns. The fuse is designed to 'blow' if a draw of more than 10 amps occurs, which will keep the horns from operating. This is a safe guard to prevent burning the wires up.I prefer not to add another relay and do extra wiring.

The referenced wiring chart (“12 Volt Wiring Gauge Requirements at specific Amps for Automotive Electrical Systems”) indicates that a ten-foot length of 18 AWG wire can safely (?) carry 15 amps at 12 volts. The size of the wire from the relay to the OEM horn is probably 18 AWG and measures between three and six feet, surely no longer than six. So, it should be able to handle up to a 15-amp draw with “normal” usage, that is, for short blasts – not laying on the horn button for minutes.

But using an “Automotive Wire Size Calculator” (http://www.gtsparkplugs.com/WireSizeCalc.html) I determined:

(a) 18 AWG wire no longer than 4.32 feet should be used to carry 10 amps at 13.8 volts (2% voltage drop).

(b) 18 AWG wire no longer than 2.88 feet should be used to carry 15 amps at 13.8 volts (2% voltage drop).

A tech representative at Wolo Horns told me that with “normal” usage each of the two horns draw about four amps, total of about 8 amps. Nevertheless, he said I should use a 15-amp fuse with the set of Wolo Maxi Sound horns. But if normal use draws 8 amps, I guess it would be OK to use the 10-amp fuse. If I stick with the OEM 10-amp fuse, will it decrease delivery of the full potential to the horns?

I want the full potential but I don’t want to burn up wires. If I am wrong, I need to hear about it.

Thanks for help.

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