Re: Horn installer in VIC
Posted: Sat Jan 19, 2019 1:51 pm
It's really not that difficult. I do electrical design for DC systems daily as my job.
Look at the maximum current requirements of ALL the horns you want to install. Look at the stock fuse for the stock wiring harness. If it's 5/10/15A (and maybe check the owners manual to make sure it hasn't been replaced with an incorrect fuse at some point), then that means the existing (stock) harness is going to be okay up to that current without any issues.
Then, if you are splitting the harness at the horn, such as to install 2x horns on the same harness, make sure the current requirement of the 2x horns is less than the fuse (and thus the harness). Fuses are placed up-stream to protect devices AND cables down-stream.
Now, if your new horns require more current than this (such as air horns), then YES, you should be looking into another solution.
Also keep in mind that fuses and cables don't melt or burn immediately. They will take a sustained current of a certain value for a certain time before they heat up beyond what the insulation is rated for. Typically horns aren't used in a sustained fashion, so keep that in mind if you are sizing up a new harness. No need to go 10 gauge wire, etc. unless you really really need it.
As for relays, if you are putting one in, make sure you choose an appropriate relay. You can always check the coil resistance to determine what the coil current will be (which is the low-power side of the relay) for a certain voltage. ie. 130 Ohm coil resistance at 12V is going to require about 100mA to hold the relay closed.
Look at the maximum current requirements of ALL the horns you want to install. Look at the stock fuse for the stock wiring harness. If it's 5/10/15A (and maybe check the owners manual to make sure it hasn't been replaced with an incorrect fuse at some point), then that means the existing (stock) harness is going to be okay up to that current without any issues.
Then, if you are splitting the harness at the horn, such as to install 2x horns on the same harness, make sure the current requirement of the 2x horns is less than the fuse (and thus the harness). Fuses are placed up-stream to protect devices AND cables down-stream.
Now, if your new horns require more current than this (such as air horns), then YES, you should be looking into another solution.
Also keep in mind that fuses and cables don't melt or burn immediately. They will take a sustained current of a certain value for a certain time before they heat up beyond what the insulation is rated for. Typically horns aren't used in a sustained fashion, so keep that in mind if you are sizing up a new harness. No need to go 10 gauge wire, etc. unless you really really need it.
As for relays, if you are putting one in, make sure you choose an appropriate relay. You can always check the coil resistance to determine what the coil current will be (which is the low-power side of the relay) for a certain voltage. ie. 130 Ohm coil resistance at 12V is going to require about 100mA to hold the relay closed.