Installing air horn....need wiring help?

[cav-mad-gav]

Hi peops.

I'm stuck!

I cant figure out the wiring need for a air horn kit.

No instructions with the kit either.

I want to install it on a seperate switch.

From looking at that, how do i put it on its own switch? and forgive my dumbness but the new switch, should it be positive or negative?

any info anyone?

thanks

[Phil-E]

You would need to bypass the existing horn and have another live from going to the switch you want to use and put that in place of the live coming from the existing horn.

So just ignore the existing wiring...

Get a live from fuse box or battery into relay, relay to air horn, then earth to air horn, then live to new switch, earth to new switch, and then live from new switch to input of relay.

Hope you understand that!

Phil

[cav-mad-gav]

kind of lol 1st of cant earth new switch its only 2 pin.

Where do i put inline fuse?

I'd need to earth the relay too dont i?

[andrew_lumb]

This is what you want - just ignore the existing horn.

Or, you could even borrow the live feed to your existing horn to act as the switch for your new relay

[cav-mad-gav]

brillo, got it sorted now, just gotta find where i can get a wire through to the cab from engine bay??? and where to steel a live feed from for the switch

[fordfan]

Hope you used the correct grade of cable for 87 and 30 of the relay. 30A implies that the horn will take upto 360 watts of power.

[vRSLen]

Hope you used the correct grade of cable for 87 and 30 of the relay. 30A implies that the horn will take upto 360 watts of power.

My thoughts too, must be one hell of a compressor

[andrew_lumb]

i would have taken the feed from the existing horn in the engine bay to switch the new relay - this retains use of the steering wheel horn push.. or is it this you are specifically trying to avoid?

[cav-mad-gav]

thats what i was avoiding doing, as i will still have the original horn in place.

as for the cable rating, i dont know lol

to be honest that diagram is off one website i found and he upped the ampage not sure why, the compressor doesnt actually say what it will draw so its all guess work

[cheezemonkhai]

Work and then set fire to the cable if it's not rated to 30A and the fuse is 30A rated.

The siebel dual tone compact air horns can work off a 10 or 15A fuse, so if you need 30A you must have one hell of a compressor.

[cav-mad-gav]

like i said i only got the 30a thing from a website, the compressor that i've got doesnt actually tell me or have any instructions with it as to what amp's it'll draw, so i figured bigger is better? lol

[cheezemonkhai]

a 30A fuse on a 10A wire will let the wire catch fire if 30A is drawn.

Your wire should be able to take more current than the fuse so that if too much current is drawn the fuse pops rather than the car catching fire due to the wire burning. That is afterall the whole point of a fuse as otherwise you might as well stick a nail in it.

[dan_the_v8man]

its only a 30A spike, the compressors aren't continuously rated for 30A

[cheezemonkhai]

No but if you pull a 30A spike down a 10A cable you are asking for problems. The cable should always be higher rated than the fuse.

[dan_the_v8man]

i agree the fuse should always be rated to the cable as its there to protect the cable. the cable should be capable of taking the starting spike.

what size cable are you using gav? (more than likely stamped/printed on the cable some where in either mm2 or AWG)

[VWD]

Possibly telling granmothers about getting thingsout of eggs -but here goes .

Derived from Ohms Law is a power equation relating ohms,amps and volts to give you the power used in a circuit .

Basic equation is W =I*V

Where W is power in watts, I is current in amps and V is voltage (surprise that's in volts too .

So if you know the wattage of the generator (most things electrical have a plate on them saying something like model no, 12v and a figure followed by W .Divide the W by 12(that'show someone came up with the notion of a 360 generator) and thats a good idea of the current .Fusing -approx double the calculation to allow for spikes .Other way is to connect a Ammeter in series with motor and sound off .

hope that goes a little way .

[dan_the_v8man]

Im an Electrical and Electronic design and maintenance engineer :P

[cav-mad-gav]

I really opened a can of worms here didnt I lol

the only info i can see on the wire is that its 2.5mm

that any help? I'm more than confident it will cope with this guess of 30Amps needed. lol

[cheezemonkhai]

Im an Electrical and Electronic design and maintenance engineer :P

When you say that do you mean low voltage or mains or high voltage

I'm guessing you mean circuit boards etc