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Random Quote: Boats......If it isn't one thing, it's another.
Doesn't make any sense.
If the distribution panel has individual fuses for each accessory, I would have a single fuse/breaker rated at the max capacity of the panel between it and the battery.
Doesn't make any sense.
If the distribution panel has individual fuses for each accessory, I would have a single fuse/breaker rated at the max capacity of the panel between it and the battery.
CG requires a fuse or breaker within a short distance of the source of the power (in this case the battery). If there is more than one feeder between the battery and the panel, then each feeder needs one.
To the original question - Don't know why you'd want more than one feeder, but technically it will work. As long as you have overcurrent protection rated for the size of THAT feeder on all of them, you're safe.
Also, if the feeders do not come together on the input stud of the panel, then the wire they join to has to be capable of carrying the current of ALL 3 feeders or else it needs its own fuse or breaker.
Just be aware that you will be replacing fuses in sets of three. When one goes, the load will be distributed across the remaining two, which will likely pop another, then the final one will go.
And make sure that the fuses are sized to the smaller of wire gauge and length, or combined load load.
__________________
Terry Jason 35, Yanmar 370 hp, Lots of fun at a leisurely pace
That's basically what I have (2 batts and selector) but my switch panel includes circuit breakers so I only have fuses on stufd that doesnt use the panel.
I did not know CG says I need fuse closer to the battery so I'll add that to my upgrade list. It does make sense but I've seen a lot of boats that dont have them.
__________________ I'm not a boat expert, I just read THT!
This is the first time I have seen such a setup with 3 fused Feeder-Wires.
It doesn't make sense to me, if one wire shortens out and blows the fuse the down stream side of the wire is still hot.
Is this acceptable?
It does not make any sense. If you created this setup, shame on you. If someone else did it, shame on them. You want one wire from the battery to the distribution panel and you want a fuse or circuit breaker (sized for the wire feeding the distribution panel, not the capacity of the panel) located within seven inches of the connection to the battery or battery switch.
I will redo this unreasonable set up. I still can't believe that this is how it was wired by the factory or by the dealer. And I don't know how much rigging the dealer did in this case. Maybe someone can shine a light on how that works.
I know the dealer installed the Windless and did an excellent job on wiring it with the appropriate breaker close to the source of the power.
I feel pretty confident in rewiring the feeder wires myself with a proper circuit protector. Already have enough Ancor 6 AWG Boat Cable to do the job.
"The 12 Volt Bible" and "Powerboater's Guide to Electrical Systems" I feel are a great resource to do the job right.
__________________ don't try this at home....i'm a profesional......
i know it's misspelled-it's a joke...get it???
jim anderson jimmy's marine service llc
a 5 star wrenchin' whore !!!
If you have a short that blows any one of the fues it should blow all three fuses. A short on the load side of the first fuse will show up on the load side of fuse two and fuse three by back feed.
I'm going to exagerate here a bit to demonstrate why it might be wired that way. Let's say that you want to wire for an ultimate load of 200 amps at 12v with the fuse box 30 feet away and not wanting more than a 3 percent voltage drop. For this you would need a feed of 4/0 wire. Since 4/0 wire is quite bulky you could use two feeds of 2/0 wire to feed the fuse box and run them through separate chases. What I suspect here is that whoever did the wiring used the same principal. Instead of one bulky wire they used multiple wires to feed the fuse box. As long as they're fused properly there should be no problem but it's not something I would like to do on a boat. I would break my load up over multiple fuse boxes with a single fused feed to each fuse box.
ABYC calls for a fuse on each positive lead within 7" of the battery. I can see where if the factory wiring was not adequate, a second parallel wire was added. This does not mean that either circut is over loaded, but the owner wanted to keep voltage drop to 3% rather than 10%. He added the proper fuse. Many boats from the factory are in-adequately wired--the wire to the console, where the main bus bar is, is small and the voltage drop is over 3%. Thus the second wire is added. This is neither unsafe, nor "dumb". It will allow the electronics to have adequate voltage. The "shame on" should be to the factory for not providing adequate wiring to begin with. This under wiring is much more common than you may think!
As has been said, NO, this is not acceptable. Three fuses in this arrangement would provide current capacity for 3 times the rating of an indivual fuse. If one of these wires were to short at the load This wiring WILL get you in trouble and MIGHT CAUSE A FIRE.
This probably a code/standards violation. Use one fuse and one wire per leg. If you need more capacity, get a bigger fuse, and a bigger wire. . Why are there three wires from one point to another point? Why NOT use one wire?
The inspectors did the right thing sending you back to get this fixed - and your doing the right thing fixing it.
Here's a link to a cool calculator that tells you what the voltage drop is in a length of wire:
At (nominally) 12V, a wire that causes a 1V drop at 10A current will generate 10 watts of heat. If it is along the length of the wire, fine, but what usually happens is that a crimp will get corroded, and present high resistance at the connector. Minimum use of connectors is important.
Fuses are designed to protect the wire. For that setup to work properly all three feeder wires should have the same size fuse and that fuse size should not exceed 1/2 the ampacity of the smallest conductor. This would defeat the purpose of running the extra conductors other than for voltage drop. One properly sized conductor would be best with the proper sized protection. If the 3 conductors were separated and each ran a different load center that would be fine.
Mike
Well that settles it - "Bad Idea" to illustrate some times it's good to look at the diagram again.
If all three individual Fuses were 100% of the ampacity for each wire and if #1 feeder shortens out it could blow #1 fuse first. this would than result in #1 wire to be fused by both fuses #2 and #3 and 200% of the ampacity resulting in a burned out wire with the 2 fuses left intact
Or it could just burn the #1 wire and all three fuses would stay intact since all three fuses together would be 300% of the ampacity of # 1 wire.
I still can't belief my new boat came wired like this.
The rule about the distance from the battery is also two fold-within 7" of the power source or within 42" if the wire is sheathed. The definition of sheathed is some additional covering other than the wire insulation, meaning split casing, wire loom, or even a continuous wrap of electrical tape will make it up to ABYC standards. The diagram looks stupid. The only reaso I can think of was that the original circuit was tested at some point and they found it had too small of a conductor. The ABYC standard says that you have an allowable voltage drop of 10% for non essential systems (items not related to safety or navigation), and 3% on essential systems. My bet is that this was tested at some point and found to be over the allowable voltage drop, so they added wires instaead of rewiring with a single larger wire. Just not a smart way to do it.
Well that settles it - "Bad Idea" to illustrate some times it's good to look at the diagram again.
If all three individual Fuses were 100% of the ampacity for each wire and if #1 feeder shortens out it could blow #1 fuse first. this would than result in #1 wire to be fused by both fuses #2 and #3 and 200% of the ampacity resulting in a burned out wire with the 2 fuses left intact
Or it could just burn the #1 wire and all three fuses would stay intact since all three fuses together would be 300% of the ampacity of # 1 wire.
I still can't belief my new boat came wired like this.
Well of course that setup is bad and should be fixed, but a worst mistake would be fusing to
100% of the attached wire. In reality, if fused to the standard 70%, that short would likely blow
all the fuses before the #1 wire section would burn. Fuses are fast and the #1 wire would probably
take more time to develop resistance as it starts burning which would prevent the fuses from blowing.
Now circuit breakers, thats a different story.
I've seen something similar before back in the day when larger fuse holders were hard to come by
and the installers would put 2 30 A fuse holders at the battery for Audio amp that draws 40A or so.
Is this Electrical setup acceptable? 
