12 volt fuse box.

[wolfscott]

Hello all, I need some help here. I have a '75ish Westerner Tri-hull, with a Mercruiser 165 I/O. All of the wiring from the dash runs into one large bundle of wiring connecting to the engine. I want to rewire the entire boat, and at the same time add a few new items. Namely, a power point for GPS, Fish finder, etc. as well as a few more running lights. Do I need to, or should I install a fuse block with the new wiring? It would seem logical to do so, and if so, is there a special marine type designed for wet locations? Any help or ideas would be greatly appreciated.

 

[jayhanig]

Re: 12 volt fuse box.

Definitely there are marine spec fuse blocks and that's what you ought to use. You also ought to buy two bus bars: one for hots and the other for grounds. They will allow you to make rhyme and reason out of your present rat's nest. You just have to run one hot and one ground to the back of the boat and tie everything under the panel to the bus bars (with the fuse panel on the hot bus). Heat shrink is your friend in the marine environment.

 

[ziggy]

Re: 12 volt fuse box.

Do I need to, or should I install a fuse block with the new wiring?

seems like a good idea.

i wanted to add a few electric items to my boat too when i got it. + i had the horn and radio scabbed into instrument cluster power. i wanted that gone.

plenty of fuse panals available right here on iboats. http://www.iboats.com/Marine-Fuse-B...3407812--**********.975619106--view_id.216615

myself, i ran two fat wires from the helm back to the batt. fused the + lead right after the batt. connection.
used one of them fuse blocks in the link and stuffed it under the dash. works great.

the fat wires are power and neg. coming from the batt. has room for six different items. i used four. neat and concise.

 

[LippCJ7]

Re: 12 volt fuse box.

Nothing wrong in how Jay does it but I did mine a little bit different, mostly due to the stereo system, I ran the appropriately sized positive and negative wires(in my case 4 gauge welding wire) from the battery to a positive and negative insulated post I installed under the helm, from there I installed a hot fuse panel and a ignition fuse panel that I wired from the positive insulated post through a 60 amp relay using the accy position on the ignition switch to trigger the relay. By doing this I have all the power I need for my stereo, depth finder what ever. The positive wire from the battery has a 150 amp resetable circuit breaker 12" from the battery, very safe and very easy to add to once the base system is installed, Can not agree more with Jay on the heat shrink...with heat activated glue!!

Also you can get alot of this info in the electrical section of the forum but I am sure the Mods will move it for you

 

[ziggy]

Re: 12 volt fuse box.

Can not agree more with Jay on the heat shrink...with heat activated glue!!

that was a nice way of telling me i was a slacker on my sta-con connectors. :facepalm:.. someday i'll remidy that. agree, proper connectors is the way to go. and i didn't use proper connectors..

 

[LippCJ7]

Re: 12 volt fuse box.

no no not at all, your just going to be replacing them!!!! Not a slacker....rookie maybe but not a slacker!

To be honest I was going to be right behind Jay but you got in before I did!

 

[Stachi]

Re: 12 volt fuse box.

Heya Lipp, I like the idea of a fixed mounted circuit breaker as opposed to an inline fuse close to the battery. I will do this when it is time for wiring on my restore project (pictured below) . I am curious, maybe due to my own lack of knowledge , why the circuit breaker you use is 150 amps ? That seems high to me , but what do I know ??

 

[LippCJ7]

Re: 12 volt fuse box.

Stachi, The 150 amp breaker is at the battery from there I have 14' of 4 gauge welding wire to the helm, if not for the breaker this wire would be unprotected, but at the same time I have to supply the power for my stereo as well as all fused loads of both fuse blocks + a little fudge for future expansion, remember even the switched fuse block is run off the main 4 gauge positive wire from the battery it just has a large relay to turn it off.

So I have the Stereo(2 amps) which are 100 fused amps(not actual load) then the two fuse blocks, I am not overly worried about the size of the breaker just that there is enough supply with protection, since each load is independently protected further up the line...

Actually I need to rephrase this, the breaker is not at the battery rather my battery switch.

 

[Stachi]

Re: 12 volt fuse box.

Thanks Lipp , the stereo explains the large breaker...cool...lol

 

[NYBo]

Re: 12 volt fuse box.

The breaker protects the wire, which in this case is heavy stuff to be able to carry the juice for all those goodies.

 

[Stachi]

Re: 12 volt fuse box.

The breaker protects the wire, which in this case is heavy stuff to be able to carry the juice for all those goodies.

I understand the size of the wire , and the need for the breaker. I am an auto mechanic ...thats welding wire... what was baffling me was the need for 150 amps of load . Thats alot of amps... sounds like good toys aboard !

 

[NYBo]

Re: 12 volt fuse box.

BTW, welcome to iboats, Scott!

A fuse panel like this has a negative buss bar built in, so this would be all you would need to buy. They are available with more circuits. Buy one with more circuits than your current needs so you have room for expansion.

 

[LippCJ7]

Re: 12 volt fuse box.

I understand the size of the wire , and the need for the breaker. I am an auto mechanic ...thats welding wire... what was baffling me was the need for 150 amps of load . Thats alot of amps... sounds like good toys aboard !

Well I don't believe in doing anything twice, if your gonna do it right do it right the first time 2 600 watt amps sounded about right!! but they are 100 amps of that load at 50 amps each(fused) I could have gone actual load value but since I wanted that breaker to have fudge in there anyway I just went with the total fused value of the loads knowing that the loads were fused anywhere from one and a half to twice the actual load of the item being fused, its definitely big but I am kinda thinking about maybe a pole and some lights and......

 

[wolfscott]

Re: 12 volt fuse box.

Hello all, I need some help here. I have a '75ish Westerner Tri-hull, with a Mercruiser 165 I/O. All of the wiring from the dash runs into one large bundle of wiring connecting to the engine. I want to rewire the entire boat, and at the same time add a few new items. Namely, a power point for GPS, Fish finder, etc. as well as a few more running lights. Do I need to, or should I install a fuse block with the new wiring? It would seem logical to do so, and if so, is there a special marine type designed for wet locations? Any help or ideas would be greatly appreciated.

WOW!! I didn't expect so many replies. You guys are awesome. Thank you so much. I feel alot more confidant about this job now. I do all of my own vehicle mechanics, but this is the first electrical for the boat. I would like to assume then that since this is a 12 volt system, the same basic concept would apply as to a vehicle, as far as grounding is concerned? or am I wrong there. I see the block with the grounding buss, that leads me to that question. Also, aside from here, where would one get a fuse block for the boat? Probably at the boat shop? I know these sound like foolish questions to you guys, but I am one to get all of the info first before trudging all over Las Vegas trying to locate parts. And once again, thank you all for the help.

 

[Silvertip]

Re: 12 volt fuse box.

You can get what you need right here on iBoats (click the Marine Store button at the top of the page). You don't need a marine store either. Even some WalMart stores have boating supplies. Cabelas, Bass Pro, or any department store that sells boating supplies can often be the most reasonable source of boating equipment.

Grounding on a boat is different than a car. You obviously can't ground to the hull on a glass boat and you shouldn't ground to the hull of a tin boat. The ground buss on a fuse/breaker panel is the central ground for all accessories. That buss is connected directly to the negative post of the battery via a single 10 gauge wire (or larger if you have a bunch of accessories). Also be aware that there are two electrical systems on a boat. The instruments are powered via the ignition switch which gets its power via the harness running to the controls from the engine. The fuse panel itself is powered from the two 10 gauge (or larger) wires directly from the battery. The reason for this is that the ignition switch and the engine harness is not designed to handle the high current load of the other boat accessories. there are a couple of generic boat wiring diagrams in the "stickies" at the top of this page.

 

[NYBo]

Re: 12 volt fuse box.

WOW!! I didn't expect so many replies. You guys are awesome. Thank you so much. I feel alot more confidant about this job now. I do all of my own vehicle mechanics, but this is the first electrical for the boat. I would like to assume then that since this is a 12 volt system, the same basic concept would apply as to a vehicle, as far as grounding is concerned? or am I wrong there. I see the block with the grounding buss, that leads me to that question. Also, aside from here, where would one get a fuse block for the boat? Probably at the boat shop? I know these sound like foolish questions to you guys, but I am one to get all of the info first before trudging all over Las Vegas trying to locate parts. And once again, thank you all for the help.

Just click on the link in my previous reply.

 

[LippCJ7]

Re: 12 volt fuse box.

WOW!! I didn't expect so many replies. You guys are awesome. Thank you so much. I feel alot more confidant about this job now. I do all of my own vehicle mechanics, but this is the first electrical for the boat. I would like to assume then that since this is a 12 volt system, the same basic concept would apply as to a vehicle, as far as grounding is concerned? or am I wrong there. I see the block with the grounding buss, that leads me to that question. Also, aside from here, where would one get a fuse block for the boat? Probably at the boat shop? I know these sound like foolish questions to you guys, but I am one to get all of the info first before trudging all over Las Vegas trying to locate parts. And once again, thank you all for the help.

Most say that the only foolish questions are those that go unasked and this is could not be more true in electrical systems on boats. The only thing we can do is educate you to what we have found to be the best electrical practices on boats, be advised that when you find corrosion in a connection both sides of the connection need proper attention. No matter what precautions you take, it is very likely corrosion eventually will get into your electrical system, its just the nature of the beast, the benefit to all this is that boats have a way of making excellent vehicle electricians due to the fact we have the perfect test platform! Keep in mind to never discount the grounds they are just as important as the positive side of the circuit, something often forgotten in vehicle electrical, your boat will fix this shortcoming for you.

 

[wolfscott]

Re: 12 volt fuse box.

Hello again, and once again thank you all for the help. And I didn't acknowledge NYBo for the welcome aboard, so Thank you for that. Well, I think I have everything I am going to need. I got a 10 place fuse block, heavy gauge wire for the feed, and 16 gauge for the instruments. Now I have one more question. Since I have a 10 place block, and each of my gauges are independently wired, can I wire say a couple together, then into the fuses, or would it be wise to give each one it's own fuse. That sounds a bit like overkill to me, but maybe not. And the follow-up to that is, if I wire them all to the same fuse, what size would be right? 10A, 15A?, and if I go with separate, would 5A work for each? What I am looking for is simplicity, yet functionality. If I blow a fuse, I don't want the whole thing crashing down. Does that make sense? What I have for gauges is Fuel, Temp, Tach, and one other I can't remember, possibly a volt meter.(sorry, I am at work). I then have a bow light, and a stern light, which are both simultaneously operated by a dash switch. There is a bilge pump switch, and a blower switch, push button for the horn, and lastly the three buttons for the I/O trim. I am looking at adding a 12 volt power point, possibly 2, and maybe some more running lights. There is also possibly a stereo and speakers in the future. There is a 50Amp breaker on the engine now, with a reset. I am hoping I don't need to mess with that. So, there we have it, my simple little "Wolf Run" in a nut shell.Thanks again for the help.

 

[LippCJ7]

Re: 12 volt fuse box.

Ok there you go thinking about something and completely blowing the theory in that thought, fuses are there to protect the load of which they are fusing, by combining circuits your defeating the principal. If you say wire two loads together at twenty amps since one is a 5 amp load and the other a 15 amp load all that will happen is the smaller load will blow up because the fuse is bigger then the load is, so NO you shouldn't combine circuits, each circuit should be properly fused independently of other circuits. Yes it would be easier but now you know why fuse panels in cars have become fuse centers! If you have three power outlets (cigarette lighter outlets) then I would say ok(but I don't) go ahead and combine them but were not talking about a load that may only be used sometimes so if you want to do it right then you need independent fused circuits.

The dash lighting is one circuit so tach, fuel, volts etc lights are fused as one circuit, the gauges themselves are also one circuit as well, then the nav lights although you should have a switch that lights up the anchor light on one position and the anchor and red/green lights on the other also on one circuit but switched differently, its a little more complicated with the nav/anchor lights but its just how to properly wire the switch they are still one circuit and fused as one circuit. Horn is one circuit and I believe the trim is one circuit as well.

Clear as mud right?

 

[NYBo]

Re: 12 volt fuse box.

The gauges are powered through the motor's electrical system, not through the fuse block for the accessories.

Lipp, the fuses in the fuse block are there to protect the wiring, not the devices connected to them. Think of the wiring in your house. The breakers are sized so the wiring doesn't heat to dangerous levels before the breaker trips. The breakers don't protect your lights, stereo, etc., and you can mix loads of different sizes as long as the total draw doesn't exceed the rating of the circuit. If a device in your boat has an inline fuse in its wiring harness, that fuse will usually be of very low capacity to provide protection for the device. But an internal short can still fry delicate circuitry.