Fuses or breakers?

[jklnhyde]

I'm about to start my winter project wiring, but I'm stuck at a crucial point; do I rewire with a fuse box or a breaker box?
The boat came without a proper distribution panel and along with the usual navigation electrics, there are deck lights, cabin lights, flourecents, spotlight, storage compartment lights, etc, etc.
I want to start by using a small, breaker-equipped panel to distribute power to one or two, smaller fused panels that will each then spread out the electrical loads, and allow me to systematically pair accessories so as to not lose total power in an emergency. Is this overkill?
Most of the breaker panels I see are equipped with 5, 10 and 15 amp breakers; is this too small to allow current to flow to another fuse panel further down?
What are the advantages of using a breaker panel vs. a fused panel, besides breakers being easier to reset? Are they safer/more reliable?
Will a fused panel give me more amperage options since I can chose the amp rating of the fuse to match the accessory?
(come to think of it, can't I do the same thing with a breaker panel?!?!?)

Any advice is greatly appreciated!
Rick

 

[Barnacle_Bill]

Re: Fuses or breakers?

I would use fuses as you have a very large selection of sizes to choose from. Keep in mind that you not only have to consider to total amperage the accessories will draw but also the length and size of the wiring feeding everything. Yes you could use breakers to feed a fuse panel but its not needed.

 

[rndn]

Re: Fuses or breakers?

I vote for curcuit breakers. Why go with something that requires you carry a spare instead of just resetting the breaker.

 

[TerryMSU]

Re: Fuses or breakers?

Either should work as well. Bhile's comment on ratings is good, but either fuses or breakers are very sloppy. (A 1 amp breaker or fuse both take about 2 amps to trip.) I wonder if resetable breakers are less suitable for a wet environment than fuses. The fuses could be totally sealed. Rndn has a point as well, but it might be a bad point. Fuses you can replace, if the breaker fails you are out of luck. At least with a fuse, you can swap out with a non-critical load.

TerryMSU

 

[jklnhyde]

Re: Fuses or breakers?

I agree with both views, but why do high-end boats have breaker panels? There must be some kind of advantage over fused panels if they show up on expensive boats...

 

[tashasdaddy]

Re: Fuses or breakers?

the advantage # is not having to hunt replacement fuses in the dark. i remember as a child, my grandmother having to find the flash light or oil lamp, then finding the correct fuse, to get the lights back on.

either system will require proper maintainance, in a salt water environment. you can get any size panel and breaker you need.
http://www.unipowercorp.com/Unipowe...e499909cfe88&gclid=CIX7hLK96pYCFQKNxwod11yUOg

 

[Bondo]

Re: Fuses or breakers?

Ayuh,....

When did my barge, I went with 3 seperate ATC fuse blocks,...
2 are fed independently(from different batteries),+ the 3rd off the same leg as 1 of the others....

A few years ago, I stumbled onto self-resetting breakers that pop into the ATC slots...
I get them at my local Napa,+ they come in Most amperages....
Now,...
The Only things on Fuses are my radios, as their amperage draw is Soo low...

 

[drewpster]

Re: Fuses or breakers?

Bare in mind that the reason you have fuse/ breaker protection is to protect the wire, not necessarily the consumer powered by the wire. I am not an engineer so take my opinion for what it is worth. It is my understanding that it is best to rate the fuse or breaker based on two things:

1) The total current needed to power all the consumers in the circuit, and;
2) the total current the wire can carry safely.

In short, you need a fuse big enough to power everything, and small enough to trip before the wire gets hot or burns in the event of an overload.

The difference between a fuse and a breaker in terms of circuit protection is very small. However there are many different types of fuses and breakers. It is a good idea to know what each is designed to do so that you use the right one for the job. One example would be using an ignition protected breaker in a engine compartment. Another example would be using a fast acting fuse to protect the circuit feeding sensitive electronics.
If you use automatic reset type breakers be advised that there are two types. Type 1 automatic breakers can automatically reset even though an overload still exists in the circuit. Type 2 automatic breakers are designed to open, and remain open, until the overload is fixed. It is important to know the difference.

It is a good idea to build in redundancy in a boat's electrical system. It is best to think in terms of what CAN go wrong instead of what cannot. In larger vessels having complicated electrical systems it is recommended to design the system using individual main branches feeding sub panels. That way if a failure occurs downstream of the sub panel or in that panel's main feed other branches will continue to work unaffected by a major failure. (like fire) In smaller vessels a lack of space my require the use of a single panel fed by a single main cable. In smaller boats safety can be built in by powering essential systems, like engine, navigation and radios, through individual main branches fed from a main power buss. A separate panel can be used for non-essential items.
In my boat I use a battery switch panel to control all battery functions manually and automatically. I use separate breakers to power all engine functions, bilge pumps, and yet another to power radios and my navigation equipment. (some day when I can afford them) I also use separate breakers for high current items like windlass motors and head macerators. I use two main feeds to power a sub-panel. That panel powers everything else. In my view a good electrical system does not depend on everything working perfectly. A good electrical system works when everything is going wrong.

 

[NSBCraig]

Re: Fuses or breakers?

I put in breakers. I really don't want to have to care fuses along with everything else, but then fuses are not very big.

Breakers are seal though a fuse panel by nature is not.

 

[waterinthefuel]

Re: Fuses or breakers?

As an aircraft mechanic in training who studied the hell out of both, I would say it comes down to personal preference. If you want to bring along fuses with you, then go with fuses. If you don't, use breakers. They both serve the same function.

However, I would say keep one thing in mind. If you don't have a lot of electrical knowledge and something happens that you pop a fuse, you may go through several fuses before you discover the problem. With a circuit breaker you get unlimited numbers of "mulligans."

 

[Hanr3]

Re: Fuses or breakers?

Bare in mind that the reason you have fuse/ breaker protection is to protect the wire, not necessarily the consumer powered by the wire.

Not always true. For general circuits the fuse/breaker should trip before you fry the circuit. Lights for example are a general circuit.

For sensative electronics or electrical motors you should rate the fuse/breaker for the equipment. It would be better to trip a fuse/breaker before an electrical motor overheats, shorts, and starts a fire. It would be a good idea to protect the bilge pump on its own circuit. Kind of screwed if your bilge pump catches fire and burns a hole in your hull. As for sensative electronics its far cheaper to pop for a new fuse than it is for a new fish finder.

In all cases the wire must be rated to carry the max fuseable load over the entire distance without overheating and shorting out.

As for the motors, if you go with fuses or breakers make sure they are rated for the initial start up load of the motor. During start up a motor will draw more power than what is required to maintain running speed. Conversly, if your powering a sensative circuit, dont use a fuse/breaker rated for motors.

Regardless how many fuse/breaker panels you use, install one battery cut off switch that cuts power to everything instantly.

 

[Hanr3]

Re: Fuses or breakers?

However, I would say keep one thing in mind. If you don't have a lot of electrical knowledge and something happens that you pop a fuse, you may go through several fuses before you discover the problem. With a circuit breaker you get unlimited numbers of "mulligans."

Ain't that the truth. I burnt up 5 fuses trouble shooting an electrical problem while 4 wheeling. I kept blowing my fuel pump fuse. Turns out I ripped the oil pressure wires off the oil pressure switch while wheeling earlier in the day. However it didn't create a problem until I did a water crossing. Shorted out. I finally found it, the wires managed to hang next to each other, every bump they made contact and popped the fuse. I think the water crossing managed to free the wires so they could hang free.

 

[triumphrick]

Re: Fuses or breakers?

I would always prefer a circuit breakerto a fuse in a marine environment. The higher end boats use them because they are more reliable and just the inherent mounting of the fuse in a fuse holder creates problems. Lot's of intermittent problems with fuses are caused by the corrosion around the fuse in the fuse holder. None of that applies with a circuit breaker. I liked the "mulligan" comment aswell...

 

[TerryMSU]

Re: Fuses or breakers?

Bare in mind that the reason you have fuse/ breaker protection is to protect the wire, not necessarily the consumer powered by the wire. I am not an engineer so take my opinion for what it is worth. It is my understanding that it is best to rate the fuse or breaker based on two things:

1) The total current needed to power all the consumers in the circuit, and;
2) the total current the wire can carry safely.

In short, you need a fuse big enough to power everything, and small enough to trip before the wire gets hot or burns in the event of an overload.

The difference between a fuse and a breaker in terms of circuit protection is very small. However there are many different types of fuses and breakers. It is a good idea to know what each is designed to do so that you use the right one for the job. One example would be using an ignition protected breaker in a engine compartment. Another example would be using a fast acting fuse to protect the circuit feeding sensitive electronics.
If you use automatic reset type breakers be advised that there are two types. Type 1 automatic breakers can automatically reset even though an overload still exists in the circuit. Type 2 automatic breakers are designed to open, and remain open, until the overload is fixed. It is important to know the difference.

It is a good idea to build in redundancy in a boat's electrical system. It is best to think in terms of what CAN go wrong instead of what cannot. In larger vessels having complicated electrical systems it is recommended to design the system using individual main branches feeding sub panels. That way if a failure occurs downstream of the sub panel or in that panel's main feed other branches will continue to work unaffected by a major failure. (like fire) In smaller vessels a lack of space my require the use of a single panel fed by a single main cable. In smaller boats safety can be built in by powering essential systems, like engine, navigation and radios, through individual main branches fed from a main power buss. A separate panel can be used for non-essential items.
In my boat I use a battery switch panel to control all battery functions manually and automatically. I use separate breakers to power all engine functions, bilge pumps, and yet another to power radios and my navigation equipment. (some day when I can afford them) I also use separate breakers for high current items like windlass motors and head macerators. I use two main feeds to power a sub-panel. That panel powers everything else. In my view a good electrical system does not depend on everything working perfectly. A good electrical system works when everything is going wrong.

Unlike Drewpster, I am an electrical engineer (although technically, I can not say I am one as I do not have a Professional Engineering License.) I am also a former employee of a circuit breaker manufacturer (for aircraft circuit breakers). Everything Drewpster said is absolutely correct. Generally, you should not plan on fuses or breakers protecting sensitive electronics. There are special fuses that will blow fast enough to protect electronic devices, but these are relatively rare. The fuses and circuit breakers that you have access to are intended to protect wires and mechanical devices like motors and relays. We used to say they were to prevent smoke and fire damage. By the way, aircraft and boats have a similar risk in case of smoke and/or fire damage. Both can be a long way from safety, so don't cut corners.


TerryMSU