Fuse or circuit protector

[kbert1171]

I just purchased 2 Minn Kota DeckHand 40 anchor winches. They have built in circuit breakers, but should I also run fuses to them as well?

 

[poconojoe]

Normally the circuit protection should be at the source (battery). The purpose of the fuse or breaker is to protect the wire from burning up due to a short or an overload.
So, the fuse or breaker should be at the battery and be rated according to the gauge of the wire.

 

[gm280]

They make bolt on breakers that attach to the battery terminals. I would add one and also leave the one at the trolling motor intact as well. Just make sure the battery breaker is large enough to handle inrush surge current of the trolling motor on the highest setting or you will be resetting it a lot.

 

[kbert1171]

Not a trolling motor. It's an anchor winch. But i imagine the principle still applies.

 

[kbert1171]

I am installing a fuse block, as there was absolutely nothing before. Just a bundle of wadded up wires, zip tied to the compartment. Everything will run through this, but some devices have their own inline fuses or CB's. I was simply curious as to weather I should run the fused items and the items with CB technology already installed, through the fuse panel as well.
I have a separate CB for the trolling motor, so it will not be run through the fuse panel.

 

[Greg558]

I just purchased 2 Minn Kota DeckHand 40 anchor facetime app winches. They have built in circuit breakers, but should I also run fuses to them as well?

fuses and circuit breakers. Fuses are devices that melt or destruct at a certain current flow, like five amps. Once they melt they must be replaced. Circuit breakers are mechanical devices that trip and open the circuit without damage to themselves. Since circuit breakers can also be used as switches, they are frequently stacked in a row in a distribution panel. They are also measured by the current (amperage) it takes to cause them to trip.

 

[jhande]

Yep, same principal has in homes.
Old glass screw in fuses blow and have to be replaced.
Now circuit breakers that trip (turn off the circuit) and can be reset (turned back on).
They both server the same purpose, protect the wires and appliances from burning if something goes wrong by shutting of the electricity.

As far as placement is concerned, closer to the power source is mostly do to convenience. The amps travel quick enough to trigger the safety device any where in the run.

Back to the OP's question...
Running both a fuse and circuit breaker is really over kill. But if it makes you sleep better at night there's no problem or reason not to except the extra expense. Just make sure to match the amps or the circuit breaker to the fuse.

 

[froggy1150]

You MUST protect the whole circuit at the power source. The wire must be at least 125% of the ampacity of the protection. You can also protect the device where it takes its power from the wire run. That should be what the dataplate states. If you change wire sizes smaller you MUST again protect for the smaller wire size @ at that tap. And the protection must be at least 125% of the smaller wire size. If you ground a wire a foot from the battery but your fuse is 13 inches down that foot of wire is going to melt red hot and start a fire

 

[froggy1150]

I would also not rely on a circuit breaker for primary circuit protection in a marine enviorment due to the possibility of mechanical failure from corrosion

 

[jhande]

You MUST protect the whole circuit at the power source. The wire must be at least 125% of the ampacity of the protection. You can also protect the device where it takes its power from the wire run. That should be what the dataplate states. If you change wire sizes smaller you MUST again protect for the smaller wire size @ at that tap. And the protection must be at least 125% of the smaller wire size. If you ground a wire a foot from the battery but your fuse is 13 inches down that foot of wire is going to melt red hot and start a fire

Let's try this scenario...
Run your wires from the battery to a fuse panel at the helm 2/3 the boat length. Are those fuses at the power source (battery)? NO. Lets look at the 12v DC in a automotive vehicle. The fuse box is under the dashboard, NOT at the battery/power source. If you were to worry about your negative and positive wires shorting out together then yes a fuse at the power source/battery would help.

I'm a bit confused with your statement:
"If you ground a wire a foot from the battery but your fuse is 13 inches down that foot of wire is going to melt red hot and start a fire"

A foot is only 12 inches so how are you installing a fuse at 13 inches?
Also fuses do not get installed in the ground/negative wire. They get installed in the positive wire.
Or are you trying to say that you have a wire run with a 12 inch negative/ground wire and in the positive wire the fuse is 13 inches away because they are not equal lengths away from the power source it will cause a fire? That is a big nope.
But like I said, I don't understand what you were trying to say so I'm confused!

If you're trying to say that (let's say for example) a trolling motor 20 feet (240 inches) away from the battery and has a fuse right next to the trolling motor and the motor shorts out, the wires leading to it will get red hot, melt and cause a fire? Sorry THINK again. If the wires leading to it short out together (positive & negative) than yes. But only if the insulation around both wires in the exact same location deteriorates and the bare wires touch each other will that happen.

EDIT:
Yes, you can run a positive feed wire say 20 feet long and tap into it any where you want. Just make sure all wires are of proper gauge and install the proper amp fuse into the tapping wire for the appliance, i.e. trolling motor.

 

[Horigan]

He's saying that fuses don't protect for positive shorts to ground if that short happens between the battery and the fuse. That's the benefit of placing a fuse close to the battery, reduced exposure to positive shorts to ground. This can also be handled with good wire management/placement, as is done on cars.

 

[jhande]

Thanks Rich, I wasn't sure that's why I added that to my above reply.

But in all honesty, I certainly wouldn't want to be out on the water with either really old wires (possible insulation cracking) or positive & negative wires rubbing together.