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Fuse confusion, inline vs "switchboard" vs ? School me please

Old 07-21-2013, 05:12 PM
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Default Fuse confusion, inline vs "switchboard" vs ? School me please

I recently did some rewiring. It appears some items have fuses, some do not. The lights and VHF are all fused off a panel. The amp is fused inline. The GPS is fused inline. Everything else, which consists of various pumps, backup GPS, and LED lights are not fuse protected.

Should they be? What is the best way?

I just replaced with clean new buss bars, but I would be willing to swap out for a fuse panel if its the right way. Or go inline I guess would be easier, but sloppier too. I don't like sloppy. As I understand it, a fuse panel has a small section for the negative buss, then a corresponding amount of positive screws, each protected by a fuse. Is this right?

Anybody know?

Better yet, anybody have a diagram of theirs?

I am no electrician, but I don't mind some bloody knuckles here and there. I'm not a rookie boater by any means, but I've hired out electrical stuff in the past and decided its time to learn how its done myself.
Old 07-21-2013, 05:37 PM
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I just rewired my friends 22 Whaler. Sounds a lot like your wires. He had some inline fuses and an old glass fuse panel. We swapped everything out and went with a Blue Sea fused panel. Also the Blue Sea web site has some good stuff. We wired from the battery to a Blue Sea 285 circuit breaker/switch and then to the panel. They make a 6 and a 12 circuit panel. It makes a very nice and clean set up. Good luck.

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Old 07-21-2013, 05:52 PM
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Yes I had the blue sea one on my last boat. I like their company, I have their buss bars on current set up. A few follow up questions:

Aside from the redundancy and one more place to troubleshoot, is there any harm in not removing the inline fuses?

Is there a good rule of thumb for fuse sizing. Some bigger items come with detailed fusing instructions like GPS, but for small stuff, like LED lighting, 12v accessory, and whatnot should I just run 5volt?

I know its better to run smaller than larger so you trip fuse before you burn out item, but does too little amperage hurt it?

Brad, I'm looking at a fuse block, It looks like you installed more of a circuit breaker if I'm not mistaken. I attached a pic (that is way too big) below of my basic plan. Using this system I can just remove my new buss bars and replace them with fuse protected ones.
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Old 07-21-2013, 06:01 PM
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I tried to down load a picture. Your Blue Sea panel is a good bit nicer than what we did.

I wondered the same thing about the in line fuses and going to the panel. We just took all the in line fuses out. I do not know if it matters in having 2 fuses on one circuit. Hopefully a boating electrican can help!
Old 07-21-2013, 06:03 PM
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Make no mistake brad, that's a downloaded pic. My wiring is clean, but not onslow bay clean like the pic I posted.
Old 07-21-2013, 06:19 PM
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OK finally got the picture loaded. I talked with a tech at Blue Sea a while back and he suggested the 285 breaker/switch. We added up the amps and this one is an 80 amp. I like it so you can turn off the power to the panel to work on it and the panel is breaker protected. I have the same set up on my little whaler but went with a 50 amp breaker.
Old 07-21-2013, 06:24 PM
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Damn! Guess you know all about clean wiring! That came out great. Hope mine goes that easy. It should, as I'm basically just swapping out a simple buss bar for a more complicated one.
Old 07-22-2013, 02:48 PM
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If space is an issue, you can use a seperate buss bar for the grounds with a smaller fuse block without the grounding provisions. Blue Sea also makes circuit breakers with a single large lever. You might consider those too.

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Old 07-22-2013, 04:27 PM
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These are the uses for fuses/breakers:

1. To protect the wire. If the wire shorts out, you don't want it to heat up and have its insulation catch on fire. This is the purpose of breakers in the home and often on a boat. These devices do not protect the equipment which may blow up in catastrophic ways. See below.

2. To protect the electronics. Should the equipment short out, you want to keep the current going to it limited so that it doesn't catch on fire. The fuse/breaker used to protect the wiring may likely allow way more than the desired max current as noted. For this reason, fuses are put in line with the equipment even though there is also the breaker/fuse protecting the wires and usually have small amperage relative to breakers. So nothing wrong with cascading them this way.

3. To protect the electronics from secondary damage. A shorted amplifier for example may proceed to also blow up the power supply feeding it. A fuse can blow before this happens.

As to the other question, other than convenience to have all the fuses in one place and nicely documented, there is nothing wrong with using in-line fuses. I for example am using the inline fuse that came with my NMEA 2000 power kit even though I too have the Blue Seas fuse box. I am too frugal that way .

BTW, breakers are usually too slow to work for #2 and #3. Fuses should be used instead.

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