12 Volt Airhorn Amperage

I'm fitting a airhorn into a car but It does not show me its amp strengh or wattage in order to calculate.my multimeter is rated for 10A, I'm just afraid I might damage it .its the normal red air compressor with the 2 horns and see through pipe.I'm going to use the existing factory wires for switching of the relay.Do it once,do it right - This means no short cuts. You never get paid twice for having to do the job twice because it wasn't done right the first time.

I assumed 30A for mine, probably because that was the rating of the relay it came with. Why do you want to know? Else just assume 30A. As long as the fuse protects the wiring things should be safe even if you have , to upgrade the circuit to prevent fuses blowing.

So 10gauge should work fine with a 30A fuse?Do it once,do it right - This means no short cuts. You never get paid twice for having to do the job twice because it wasn't done right the first time.

Also advise if its needed for a relay,can't I use the existing wiring as it already has a factory relay?Do it once,do it right - This means no short cuts. You never get paid twice for having to do the job twice because it wasn't done right the first time.

If your relay and its wining and fuse handle it, you can use it. That probably means it replacing your existing horn(s) which afaik are usual ~5-8A each. However a with all high current additions, I usually advise separate circuits. Ad in my case, airhorns have always been fitted with a selector switch so I can use just the OEM or plain horns and only switch in the airs for country driving or real bad situations (where they usually also trigger headlights). As to 10G, according to powerstream's American Wire Gauge table it's fine as chassis wiring (55A) whereas for power transmission (unbundled air mounting) it's only 15A though that should be ok given the short term nature of horn use. I look upon 10G as being a 150mV drop per meter at 30A which IMO is ok for a horn assuming a typical (front) battery to (front) horn short run (via a relay). Note that others here generally use other wire gauge tables, and I only use them for the raw data so I can calculate voltage drops (which is how I size my wiring) or see how they current-rate their wires (ie, my sizing should never be less than what tables state).

15-20 is normally OK, or feed in parallel from your existing horns and up the fuse to 20 amps. BTW The brand shown, the tubing is bloody awful, hot water or WD-40 to erase them on.

Thanks a lot Howie!think ill use the existing wires.looks like 12gauge.Do it once,do it right - This means no short cuts. You never get paid twice for having to do the job twice because it wasn't done right the first time.

Hi Howie/Old Spark! I have fitted the horn succesfully.I used the existing wires for switching on the relay and the horn works 100%.I have one problem,the factory keyless entry beep does not work anymore. As far as I can imagine it is still suppose to work via relay with the new horn.do you think it reseted when I removed the battery terminals? Its a Toyota corrola 2004 sedan.your feedback will be highly appreciated.Do it once,do it right - This means no short cuts. You never get paid twice for having to do the job twice because it wasn't done right the first time.

Shouldn't have made any difference.

It is a factory +tve switching circuit.ill ask the guy to check the manual out as the only wire I removed was the one wire from original horn and used it for +tve switching on the relay.thanks.Do it once,do it right - This means no short cuts. You never get paid twice for having to do the job twice because it wasn't done right the first time.