fuse/reset circuit breakers, & downriggers

[fishee2]

I have couple of questions.

My GARMIM GPS antenna 19x HVS requires a 1 AMP fuse.
(It's currently connected through inline glass fuse)

I want to connect the GARMIM GPS antenna power through a on/off rocker switch, with reset button circuit breaker.

My issue here is I can't find a 1 AMP reset button circuit breaker. Would it work with a 3 AMP circuit breaker?

My 2 Scotty downriggers connects directly to battery through inline glass fuse holder 30 amps each.

Yes, I want to connect the 2 downriggers through the on/off rocker switch. Is that a good idea or bad idea?

I am trying to clean up my wire system, and wanting to keep all the fuses in one location.

Thanks in advance for any advice or suggestions. :D

[Larry3215]

Trying to keep all the fuses/breakers in one spot can cause problems - mainly because that almost always requires extra long wire runs.

In the case of your GPS antenna, it depends on where its mounted. If it is close to the panel where the switches go, then no big deal. If its at the back of the boat, that can be an issue. The main problem with something like the GPS is that long power wires can potentially pick up interference from other power wires running from front to back in the same area.

I personally would recommend you power the GPS from the same switch/breaker that powers your Chart plotter. You want the GPS and plotter on at the same time and there is no use having the GPS on when the plotter is off, so why not keep things simple and have a single switch? A 3 amp should be plenty big enough for both if you want to do it that way.

The purpose of any fuse/breaker in any of the power lines is to protect the wires - NOT the device at the end. Most people have that backwards. Its to prevent a fire if a wire shorts - not to save the device in case of over voltage.

Anything connected directly to the battery needs a fuse/breaker at the battery or you run the risk of burning up all of wire between the battery and the fuse/breaker in the event of a short somewhere between the battery and the fuse/breaker - which could easily start a fire and/or melt other wires running in the same area. If your battery is in back and your fuse is on the panel, you risk burning up that entire length of wire if there is a short. That would make for a very bad day on the water.

The other issue is wire size verses length. Your factory downrigger wires are sized to carry the max current safely for that exact length of wire. When you add more wire, the resistance in the circuit goes up, which means the voltage getting to the downrigger goes down. That will make the downrigger run hotter and have less power. There are websites you can Google for wires size/amp load/length of run that will tell you how large the wire needs to be when you extend a run like that. Your Scotty manual probably has a table somewhere in it that gives the same information. Do NOT skimp on wire size.

BUT - even if you go with larger wire for the exta length, you still need a breaker/fuse at the battery.

I dont really see any reason to have a separate switch for the downriggers. They already have a switch and a fuse/breaker. You're just adding complexity where it isnt needed and may actually make things less safe.

Ideally, you already have one main fuse/breaker at the battery in the main power lead that runs up to your instrument/switch panel. That lead then powers the fuse block or runs to each individual breaker. If not, I would add one.

Hope that helps.

[fishee2]

Thanks for the info Larry.

I went ahead did some more research on wire length and watch a few videos about it.

And with the GPS/Chartplotter, i am going to make it one switch for it. thx

[hewesfisher]

Great advice from Larry! I'll add a few comments about the GPS and plotter. Running them off a switch is fine, but you'll still need to have circuit protection as recommended by manufacturer. Even though circuit protection devices (fuses/breakers) are there to protect the conductors, they also prevent over current conditions from wiping out devices fed by the circuit. Easier to replace a fuse than a fuse and a GPS or plotter.

I agree completely with Larry on the downriggers. ALL power leads must have a fuse or breaker within 7" of the battery positive terminal for the very reason he stated, you don't want to fry wire from your battery or batteries to the source of over current draw.

Only other comment I'll make is consider using only marine grade wire for your projects. Marine grade wire is tinned its entire length unlike automotive wire which is bare copper under the insulation. Yes it is more expensive, but IMO, worth every penny on a boat.

Here's a link to a good source for marine wire, terminals, switches, heat shrink, and more - http://www.genuinedealz.com/" onclick="window.open(this.href);return false;

I've used this place many times, great service and free shipping.

[Bodofish]

Can't agree more.... One thing I'd do is get some 30 amp breakers and replace the fuses on the downriggers. After being on boats for years, any high amperage applications are going to pop at one time or another. A breaker is a lot easier to reset than a fuse (for one reason or another you never seem to have one when you need one.). When they go and who know why I've seen them weld themselves into their receptacle's. The other thing is they also have four externalish contact places to corrode. If I was to guess why they pop, it would be improper wire connections in a marine environment. Solder and marine shrink tube should be the only way.

[Larry3215]

Great advice from Larry! I'll add a few comments about the GPS and plotter. Running them off a switch is fine, but you'll still need to have circuit protection as recommended by manufacturer. Even though circuit protection devices (fuses/breakers) are there to protect the conductors, they also prevent over current conditions from wiping out devices fed by the circuit. Easier to replace a fuse than a fuse and a GPS or plotter.

I will nit pick this just a little bit The only part of the "device" the fuse protects is the power cord in the event there is a short in the cord or an internal short in the device. It will also protect a portion of the internal circuitry but only up to the point where any internal short develops.

This is where most peoples misconception comes in. Fuses and breakers are current limiting devices. They blow when the current flow gets too hi. You cant have a "current surge" unless the voltage goes up first or there is a short somewhere beyond the fuse.

If the voltage goes up and then causes an increase in current, the device will most likely die from the over voltage long before the fuse blows. The vast majority of circuit components are far more sensitive to over voltage than over current.

In the second case of an internal short inside the device - once again -its already dead by the time the fuse blows.

So the fuse does "protect" the cord and the device from catching on fire or melting into a pile of slag, but its still going to be dead

I agree completely with Larry on the downriggers. ALL power leads must have a fuse or breaker within 7" of the battery positive terminal for the very reason he stated, you don't want to fry wire from your battery or batteries to the source of over current draw.

Only other comment I'll make is consider using only marine grade wire for your projects. Marine grade wire is tinned its entire length unlike automotive wire which is bare copper under the insulation. Yes it is more expensive, but IMO, worth every penny on a boat.

Here's a link to a good source for marine wire, terminals, switches, heat shrink, and more - http://www.genuinedealz.com/" onclick="window.open(this.href);return false;

I've used this place many times, great service and free shipping.

Excellent point on the marine wire. I learned that lesson the hard way after having to replace every wire I installed on a rebuild project after just 2 years.

Google "black wire disease"

[Bodofish]

Sorry about the rebuild.... Anything that goes in the salt, I'd give about two years with unprotected wire. Not only does it corrode and short in places, it also raises the resistance on the wire in pretty short order. People wonder about fuses in the line when you have a fuse in the device. How do we make a heating element? Increase the resistance. It would be bad news to have little hot plates all over in the interior of ones boat.......

[fishee2]

Thank you for the wealth of knowledge. I love it.

I just wanted you all to know I really appreciate the info. I am a noob with this rewiring thing. There is never enough of research. Always learn something new.

So I have a question with the main power line from battery to the Blue Sea ST Blade Fuse Block.

In the image below, the fuse max is 125 amp. Is that enough amps to go through each fuse blocks (each fuse block has a max of 100 AMPs)?

I also want to add a BLUE SEA ON/OFF switch and a 125 AMP Circuit Breaker Switch. What goes first?

Battery > 125AMP Circuit Breaker > ON/OFF Switch > BS ST Blade Fuse Block
or
Battery > ON/OFF Switch > 125AMP Circuit Breaker > BS ST Blade Fuse Block

https://www.autoelec.com.au/ssl/cms_aut ... 5026_5.JPG" onclick="window.open(this.href);return false;

[Bodofish]

OK, so we started with a FF and GPS and a couple downriggers. Are you looking to add this or replace the fuse block that should already be installed in your boat. If you are looking to replace I'd be thinking more along the lines of circuit breakers and not fuses. That said, you need to really fill us in on what you have in detail and what you're looking to accomplish.

PS if what I'm gleaning from your earlier posts that you would like to be able to turn everything off, so you don't drain the battery when you aren't underway. Maybe you just want a Battery Switch to shut the whole shooting match off with one click.

[fishee2]

I now think this is the best setup for me. This BS Circuit will be mounted close to the battery. YEP, i decided to go with fuses instead of breakers.

Sorry for so many confusion, I think my problem at the beginning is i wasn't sure what i want to setup.

[Bodofish]

That sort of setup should be mounted close to your devices with a heavy gauge wire and fuse / breaker close to your battery. That said we still don't know what you are planning to put this in, what is already there and the layout of your devices. With out all the information, all we can do is give a WAG at best.

[Larry3215]

Yup - we need more info.

How many batteries do you have? Is there a separate starting and House battery?

We need a complate list of all the items on the boat that draw power.

What engine?

Onboard charging system?

Future plans - trolling motors? crab pot puller? Anchor winch?

Where do you fish? Saltwater, big water or just small lakes or a mix?

[fishee2]

Just one battery

Nav/Anch Light, Cabin Light, Cockpit light, Horn, Bilge, VHF, Sounder, 2 Scotty DR's

1992 Johnson 70 HP 2 stroke on a 19ft C-Dory

Mostly fish on local sound and lakes

[Bodofish]

OK that makes more sense now. So you still want the fuse block as close to your switches as possible. It's not going to save you much if everything has inline fuses now. I'm guessing here but I'll bet you have a big bus block by the other switches. If it were me, I'd be just replacing the switches with a set of switches with breakers attached. Its what my boat came with from the mfg.. I understand wanting to clean it up but if you already have it all wired with fuses inline, all you would be doing is adding an expensive bus block with fuses. You could just rip it all out and start fresh but I think you would be better off served with a battery master switch if you don't have one and some new switches with breakers. Personally I like breakers a lot more than any sort of fuse but it's not a bad idea to have both as, as we know, breakers are mechanical devices and they can fail like anything else near salt water. A slightly heavier fuse or just a slow blow with the correctly rated breaker is never a bad idea... a belt and suspenders if you will. I'm still trying to get a grasp of what you're trying to do or what the problem has been up to this point. There's something driving you to want the changes.

[Larry3215]

I think your plan to clean up the wiring isnt a bad idea. Its good to have things neat and working correctly. Even if things are not broken, its your boat and you can set it up any way you want.

However, I would recommend you pause and think longer term before you start.

Its considered "best practice" to have two batteries on board if you are boating in areas where a battery failure or the motor refusing to start could put you at risk. The Sound is certainly one of those places. Its your boat and there is no law that says you must have two batteries to boat in dangerous waters, but its a dam good idea.

If you happen to get in the way of one of those big tankers or container ships - they dont stop and cant turn for crap. You could be dead if your motor wont start. Or you could get tossed on the rocks somewhere. Some lakes can get almost as bad if the motor wont start and the wind kicks up or you spring a leak and the main battery is dead.

Of course, the wiring diagram is quite different for one vrs two batteries, so you need to decide that first or you will be replacing switches and wires if you change your mind down the road.

One battery should be dedicated to starting only and the second battery is for all other electrical loads. Then you need to decide on how you will charge both batteries while you are on the water. There are different switch options depending on your choices? Do you want things automatic or do you want to (if you remember) to switch back and forth between batteries?

It all comes down to a balance between budget, safety and convenience. Higher levels of safety and convenience = higher $$