One of the other posts got me to thinking about the pros and cons of using fuses versus circuit breakers. The Hunter 31 panel, which is minimal at best, was fitted with two fuses. When it became necessary to replace one of the fuse holders, I got to thinking about using a breaker instead. Then I got to wondering why Hunter preferred to fuse to the breaker. So naturally I turn to the panel of experts to fill yet another void in my knowledge base.
Fuses vs. Breakers
- Thread starter wufibugs
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Fuses are cheaper. They work fine but you need spare fuses on hand AND the correct size. Circuit breakers are a no brainer if it trips.
I'm not sure how long circuit breakers have been around, but technology changes, and so does "the best way" to do things. The smart companies change their boats to utilize the latest technology and meet consumer demand.
I have some circuit breakers that fit into the household-stlye fuse sockets. That type fuse probably not used on boats for a long time, but just push the button and they reset, no more buying a carton of glass fuses.
I have some circuit breakers that fit into the household-stlye fuse sockets. That type fuse probably not used on boats for a long time, but just push the button and they reset, no more buying a carton of glass fuses.
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Fuseholders & fuses are alot cheaper to buy, ($5 for a fuseholder and fuse; $20 to $30 for a breaker), available just about anywhere, and they're pretty reliable. They trip faster than a breaker (exception - the slo-blo fuse type). Downsides - you need to carry spares, it's one more contact area to inspect and maintain, and if you have an intermittent circuit fault, you might go through a carton of fuses before you locate the fault.
Breakers are fairly reliable too, but they are more complex than fuses, so theoretically they can fail more often, though I haven't that many breakers fail. Breakers can also serve double duty as switches too, for some circuits.
If you've been OK with the fuses, the lowest-cost option is to simply replace the defective fuseholder. if you are thinking about breakers, You might consider replacing your fuse panel with a breaker panel, which could give you more control over all your DC loads.
For our boat I found several used DC breakers at a surplus shop for about $2 each (yes I tested them) so I now have an 8-breaker DC panel on a 19' boat
Breakers are fairly reliable too, but they are more complex than fuses, so theoretically they can fail more often, though I haven't that many breakers fail. Breakers can also serve double duty as switches too, for some circuits.
If you've been OK with the fuses, the lowest-cost option is to simply replace the defective fuseholder. if you are thinking about breakers, You might consider replacing your fuse panel with a breaker panel, which could give you more control over all your DC loads.
For our boat I found several used DC breakers at a surplus shop for about $2 each (yes I tested them) so I now have an 8-breaker DC panel on a 19' boat
I have fuses and have always thought about changing the panel for breakers. But after 9 years of service, I can't remember blowing one fuse! Granted, our electrical use is very,very light. But they seem dependable enough to me. 10 or so spares have been contained in a little section of a plastic box that holds whatnot electrical goodies and the supply seems ample.
Ideally you have both.
Breakers are best to protect circuits from overload, and catastrophic short circuits.
Fuses protect electronics. Every piece of electronics on your boat should have a fuse, 3-4 inches from the device, at the rated amperage of that device.
Also EVERY wire that runs off the positive terminal of your battery should be fused. This include the wire to your panel, your battery monitor, etc. Best way to do that is these.
http://www.defender.com/product.jsp?path=-1|328|296553|319682&id=1334558
Breakers are best to protect circuits from overload, and catastrophic short circuits.
Fuses protect electronics. Every piece of electronics on your boat should have a fuse, 3-4 inches from the device, at the rated amperage of that device.
Also EVERY wire that runs off the positive terminal of your battery should be fused. This include the wire to your panel, your battery monitor, etc. Best way to do that is these.
http://www.defender.com/product.jsp?path=-1|328|296553|319682&id=1334558
Holy moly, Jack. Every wire?? My batt cables are fused and then lead to two multi output distribution points. Must be 10 wires coming out of those two things. I understand the value of fusing, but won't adding all those connectors and splices introduce more opportunities for corrosion, vibration deterioration etc.?
Your boat's wiring probably does have adequate wiring protection from the factory, unless there have been some poorly-made additions since. It's about this time we start recommending some good 12v books.
Yes. Every wire, if it smaller than the one that feeds it. The system you have could be dangerous if smaller wires are distributed unfused. Every wire has to be fused for its rated capacity. If a small wire to a battery charger chafes and shorts, it will burn before the fuse on your battery comes anywhere close to blowing. Once you are past the breaker panel, you are OK. All wires downstream of that should be sized so the breaker trips before the wire burns. The fuse on the wire is there to try and save the attached device.
This weekend my dock mate almost burned his 2010 Hanse 40 to the waterline. He was adjusting a battery monitor that was supplied by the local yard and two wire touched in the back. The wire instantly burned down its entire length. He got 2nd degree burns on his hands pulling it out to save the boat.
Unfortunately, I agree with those above, it's economics for the builder. A piece of plastic with round holes drilled in it is vastly less expensive to produce than one with a rectangular slot and two perfectly positioned screw holes for each breaker.
Fuses can corrode in time creating a problem, but circuit breakers can and do have their faults, too. After time and use they weaken, tripping at a lower amperage and eventually needing replacement, especially when they are used as switches for high load equipment like refer units.
Some of the newer ones seem to be designed as breaker/switches (at least they are advertised as such) and I've yet to have one of these fail.
As mentioned above, fuses do have their place protecting electronics and the like in a circuit with a breaker that carries several units. Of course, for cruisers, it's a lot cheaper and handier to carry a bunch of fuses as spares than circuit breakers.
Fuses can corrode in time creating a problem, but circuit breakers can and do have their faults, too. After time and use they weaken, tripping at a lower amperage and eventually needing replacement, especially when they are used as switches for high load equipment like refer units.
Some of the newer ones seem to be designed as breaker/switches (at least they are advertised as such) and I've yet to have one of these fail.
As mentioned above, fuses do have their place protecting electronics and the like in a circuit with a breaker that carries several units. Of course, for cruisers, it's a lot cheaper and handier to carry a bunch of fuses as spares than circuit breakers.
I go from battery fuses through the switch to 40 amp breakers each feeding (6) switch panels with 15 amp breakers built in on each switch
I went with these panels as I have and A4 and they are ignition protected and the cost for me to be a bit safer was pretty much nothing as I was starting fresh
I have the 40 amp breakers as the panels have a 45 amp max cumulative load and it cost next to nothing when doing it
Any switch that feeds something that has a fuse requirement for example the bilge pump needs 5 amps to stay safe gets one
I went with these panels as I have and A4 and they are ignition protected and the cost for me to be a bit safer was pretty much nothing as I was starting fresh
I have the 40 amp breakers as the panels have a 45 amp max cumulative load and it cost next to nothing when doing it
Any switch that feeds something that has a fuse requirement for example the bilge pump needs 5 amps to stay safe gets one
Yes, I've added in-line fuses to all unprotected wires coming off the battery as well as the terminal fuse blocks.
I learned the lesson already where you disconnect the battery when working with the wiring in the back. I shorted a pos and neg wire when one got loose and touched the other buss. This caused an instantaneous melt-down. Luckily, I had my hand near the battery switch and turned off the power before it did any worse than melt the insulation and cause some smoke ... and the wires were a short run and easily exposed. I didn't have to burn my hands.
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