Duel Trumpet Type Horn Amp Rating ?

[GAJ52]

Hi

I have bought a 12v duel trumpet horn from my local chandler, unfortunately it comes with no wiring information. Each horn has two black wires one of which has a white trace - would this be the 'live' input. Also can anyone tell me what size fuse I should use in the positive feed cable ?

Thanks, Glen

 

[VicS]

Hi

I have bought a 12v duel trumpet horn from my local chandler, unfortunately it comes with no wiring information. Each horn has two black wires one of which has a white trace - would this be the 'live' input. Also can anyone tell me what size fuse I should use in the positive feed cable ?

Thanks, Glen

"Dual" !

Current could be anything up to say 20 amps if they are air horns otherwise probably 6 to 10 amps but purely guessing


Wire size would be a clue on which to base a fuse rating and connect up with wiring a little heavier than the fuse size, or larger to allow for volts drop if the cable length exceeds about 1 metre


Sensible thing is to try them on a battery with an ammeter in circuit to see what the current draw is. ( wear ear muffs!)

 

[GAJ52]

Many thanks for your help.

They are normal electric horns and the four wires (two to each horn) are surprisingly thin. The original wiring went through a circuit breaker but I think it may be faulty as the horns just splutter so thought I would try a fuse to bypass the circuit breaker - electrics are about 26 years old. If I connect the horns to a car battery they work fine so its not faulty horns and on the boat I have 4 x 110 amp batteries fully charged (13.4 v with charger connected) so its not the power supply.

Wish I new a bit more about circuit fault finding ??

 

[Trundlebug]

If you over spec the supply, it's always better for reliability in the long run.

As Vic says, draw of twin electric horns is around 5-10 amps, I wired mine via a relay to ensure the horn switch isn't loaded too much.

Allow for a current of 10 amps and then as connections age etc it will all still work reliably.

 

[Mudisox]

Mine run off the 12v socket and it's fused with 10amps, so shouldn't be a problem.

On re reading your query, If you remove the back plate you'll find an adjusting screw that will enable to tone to increase decrease so the sputtering may cease.
Good luck.

 

[Chris Pink]

You don't say how long the cable run is.

It is almost certainly volt drop in the cables preventing the horn working properly.

Horns use a surprising amount of current and the run - battery to push switch to horn and back can be quite long so the intelligent thing to do is to use a relay with fat cables (as short as practical) from battery (fuse panel) to horn and thin wires from the horn push to the relay.

I assume you've identified the positive (white tracer most likely) as you say it works when touched to a battery.

 

[GAJ52]

My boat a Birchwood only seems to use a circuit breaker panel for the supply, then to the switch or in this case a pushbutton. There are no fuses or relays in the entire system. I'm not very familier with a circuit breaker system so as far as I can see there is a high..ish current even through the pushbutton switch which seems odd, but that's how the boat was designed ??

 

[David2452]

My boat a Birchwood only seems to use a circuit breaker panel for the supply, then to the switch or in this case a pushbutton. There are no fuses or relays in the entire system. I'm not very familier with a circuit breaker system so as far as I can see there is a high..ish current even through the pushbutton switch which seems odd, but that's how the boat was designed ??

This answer assumes that by circuit breaker (which is really the correct term for a switch) you mean a thermal trip which is an over current device, making the need for another over current device (fuse) unnecessary assuming it is of the correct value of course. Most decent horn push buttons found aboard motor boats are rated between 12 & 20 amps so the original Birchwood setup is as would be expected, fine. You need to be looking for poor connections or corroded conductor causing resistance and reducing the voltage. As an example, Hella trumpet horns are rated at 6a each, so 12a a pair. Generally speaking a black with white tracer will be +?vDC

 

[GAJ52]

Many thanks for your help, that info is quite useful.

The main DC distribution panel is located under the CB and Instrument panel, its practically impossible to get to. You would think with all the hatch and cupboard space on the boat, Birchwood would have found a reasonably accessible location for the distribution panel ???