Some electrical fuse questions.

[Betowess]

I just put in a new horn and ran it from an additional powerline I had just installed - with a 2.5 amp fuse recommended for the running light- near the 12v battery. I powered the horn from this new wiring for my running/new anchor lights. All worked OK, but a little while later I blew a fuse, which I later realized was probably caused by testing the horn. I installed another fuse and it blew as well. So I went on line and looked at the specs of my new horn, only to read its rated at 4 amps. So I'm pretty sure that is what blew the fuse. On the third fuse, the light still works many hours later, and I haven't honked the horn, except for one real quick beep.

My question is can I wire in another second line (y it before the 2 amp fuse) and have a second fuse for the horn at 4 amps, so they are both on their own fuse and independent lines, but not having to pop for more battery connectors. Also, do I need to have a second/independent neg/ground line. Or can I keep both neg/grounds on the same line.

Last question. If the horn is rated a 4 amps, do you buy a four amp fuse? Do I even need a fuse for a horn? I know the running light recommended a fuse, and that is why I installed one. Thanks for any help!

 

[Mi duckdown]

Re: Some electrical fuse questions.

Are you sure the horn needs a fuse. should be on it's own circuit.?

 

[rallyart]

Re: Some electrical fuse questions.

The wire size you are using is what determines the size of fuse you need. You want to protect the wires to you don't turn them into heaters and start a fire. If you are running a horn you probably would rather have it on its own circuit because they can be problematic on a boat. You could run a bigger fuse if the light wires are capable of handling the load and run the horn on it too but I don't think you'll be happy.

 

[Betowess]

Re: Some electrical fuse questions.

The wire size you are using is what determines the size of fuse you need. You want to protect the wires to you don't turn them into heaters and start a fire. If you are running a horn you probably would rather have it on its own circuit because they can be problematic on a boat. You could run a bigger fuse if the light wires are capable of handling the load and run the horn on it too but I don't think you'll be happy.

Thanks. Here is some more info... Besides the engine 9 ga wires to marine battery, I have one wire coming from the battery, a 16ga running to a 4 gang switch with fishfinder,vhf radio, bilge, and a tiny led light under the helm. This is just a 14.5' Lund with a Yamaha 40hp 2 stroke remote. Then I just added another 16ga marine wire from the battery to a two circuit - off,on,on switch for the running light/anchor light. From this power I drew for the horn, so I guess the horn isn't on its own circuit?

I don't have a power or negative buss bar, I have just run these two lines straight from battery. The 4 gang switch has its own fuses and has always worked without a problem.

So should or can I run another (third) wire from the battery (circuit) for the horn? Could I just Y off my new second line before the 2 amp fuse, and after the Y, on this new third line put a 4 amp fuse for the horn? Would this make it its own circuit ?

None of the wires are getting close to warm with this low of amps, I believe. And do I really even need a fuse for a small 4 amp horn? It sounds like a car horn, not a fog horn on a tug! Thanks for any help.

 

[Grub54891]

Re: Some electrical fuse questions.

You would ve much happier,(and so would the boat) to install a proper fuse panel near the battery area. You would get the wiring off the battery,easier to maintain.

 

[BigDfromTN]

Re: Some electrical fuse questions.

I would for sure put a fuse on the horn. In the event of a short in the horn, button, or wire anywhere along the line the fuse will save your boat and wiring.

The 16 ga wire should be rated for 10 amps. Plenty for running lights and horn. You can Y the wire before the smaller fuse and put a 5 amp or so. OR if it were me.... I would put about a 7-10 amp fuse in the holder you have. That is below the 10 amps the wire is rated for and will keep everything safe.

Just my .02

 

[sam am I]

Re: Some electrical fuse questions.

So should or can I run another (third) wire from the battery (circuit) for the horn? Could I just Y off my new second line before the 2 amp fuse, and after the Y, on this new third line put a 4 amp fuse for the horn? Would this make it its own circuit ?

I would but "Y" off the batt and fuse the new leg of the "Y". Typically thou as you know, there is usually one main fuse at the batt. that protects the one main jumbo wire running up to the helm, at helm then, there is a fuse panel that protects each feed (horn, lights, radio, pumps, etc) with individual fuses for each load. If one pops.....say the radio(or its wire) shorts, your other three devices still work. This is what I assume you are leaning for here.......device ISOLATION. i.e., In the event your horn pops its fuse, your light still work and versa vice.

I agree and short of removing now what you just installed and then going back and adding a main wire and fuse and more wires, a fuse/switch panel and the like, just adding a second fused Y'd wire is one of the safest way given how you are currently wired. So yes.....Run another fused at batt.(before your other 2 amp fuse feed) 16awg wire, paralleling if you will the other wire that is fused from the batt. post for the horn with say that 4 amp fuse.

None of the wires are getting close to warm with this low of amps, I believe. And do I really even need a fuse for a small 4 amp horn? It sounds like a car horn, not a fog horn on a tug! Thanks for any help.

With a new suggested wire run, yes you really have to fuse it as any wire that leads away from the batt(starter being the exception) really has to be fused at the batt(or close as possible to, there are rules/guidelines) in the event the wire somewhere down stream gets to ground....., just safe that way, we don't want you on fire out there now do we?


And no.....If both the horn and lights are running off one small'ish 16awg feed wire(the non-device isolation situation as you have it now) BUT, that is fused at the batt, then no, you aren't necessarily required to have a fuse for each device at each device, just the feed off the batt that is fused at the batt for both is fine.

 

[Betowess]

Re: Some electrical fuse questions.

I would for sure put a fuse on the horn. In the event of a short in the horn, button, or wire anywhere along the line the fuse will save your boat and wiring.

The 16 ga wire should be rated for 10 amps. Plenty for running lights and horn. You can Y the wire before the smaller fuse and put a 5 amp or so. OR if it were me.... I would put about a 7-10 amp fuse in the holder you have. That is below the 10 amps the wire is rated for and will keep everything safe.

Just my .02

OK, Thanks so much BidDfromTN! I think I will just put an 8 or 9 amp fuse in , and call it good for now. Its a really tight squeeze crawling in under a 5'beam boat with its protected bow to do wiring etc. But soon I'll Y in another 5 amp fuse and run it to the horn button.

So when I do that, do I need to run an additional neg. line from the battery, or can I use the existing neg. line I have for the lights?

Thanks again!

 

[Betowess]

Re: Some electrical fuse questions.

I would but "Y" off the batt and fuse the "Y", typically as you know, there is usually one main fuse at the batt that protects the one main jumbo wire to the helm, at helm then there is a fuse panel that protects each feed (horn, lights, radio, pumps, etc). If one pops.....say the radio shorts, your other three devices still work. This is what I assume you are leaning for here.......device ISOLATION. i.e., In the event your horn pops its fuse, your light still work and versa vice.

I agree as it is the safest way given how you are wired, Run another 16awg wire in parallel if you will from the batt post(before your other 2 amp fuse feed) fused for the horn with say that 5 amp fuse.


With a new wire run, yes you really have to fuse it as any wire that leads away from the batt really has to be fused at the batt(or close as possible to, there are rules) in the event the wire somewhere down stream gets to ground....., just safe that way, we don't want you on fire out there now do we?


If both horn and lights are running off one small'ish feed wire(the non-device isolation situation as you have it now) that is fused at the batt, then no, you aren't necessarily required to have a fuse for each device at each device.

Thanks Sam am I, this is great info I was looking for! regards, B

 

[T_Herrod]

Re: Some electrical fuse questions.

Install a relay.

 

[gm280]

Re: Some electrical fuse questions.

Seriously, before you simply install a larger fuse, make absolutely certain the wire can handle that current to keep from burning your boat down... If your wire is not able to handle the extra requirements (too small gauge or too long a run) then IF the horn, for any reason, shorts, the wire would get extremely hot and a fire can start... Remember, there is no where to retreat too out on the water in the event of a fire! JMHO!

 

[Betowess]

Re: Some electrical fuse questions.

Seriously, before you simply install a larger fuse, make absolutely certain the wire can handle that current to keep from burning your boat down... If your wire is not able to handle the extra requirements (too small gauge or too long a run) then IF the horn, for any reason, shorts, the wire would get extremely hot and a fire can start... Remember, there is no where to retreat too out on the water in the event of a fire! JMHO!

Thanks, I take your advice seriously. The amp draw of the bow running light is maybe 2/3 amp to 1 + amp. I'm not sure, but its not much. The rear LED can't be much either. And the horn has a 4 amp rating. But to play it safe I'll run another line. It is 16 ga marine wire, and that should handle 10 amps is what I've heard. So it shouldn't be a problem, especially with fuses in place. Thanks for all the help guys!