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Discussion Starter #1
As you may know, I'm in the process of cleaning up my tangled mess of wiring and before I finalize the connections, I'd like to get some advice.

Question 1

The driving lights I have (Denali D2) use a 20A inline fuse which comes out of a control box. If I'm connecting the lights to a fuse block, do I really need to utilize the inline fuse as well? Couldn't I just use the 20A fuse and put it into the fuse block instead? I would just keep the empty inline fuse holder, as it gives me the additional length of wiring to get to the fuse box.

I believe the control box & 20A fuse is used in case additional lights are going to be mounted.

Question 2

I'm aware there's a formula for determining the correct type of fuse for each component, but for the sake of curiousity, is there harm in putting a higher amp fuse than what's needed? For example, if something normally requires a 5A fuse, what would happen if I threw a 10A fuse in there?
 

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There is no need to double fuse. If you connect to a fuse box, you can remove the in line fuse.

The fuse is there to protect the wire from overheating. Too large a fuse can allow a wire rated for a smaller fuse to be damaged or even cause a fire if a short circuit occurs. It's the same situation as replacing a house fuse or circuit breaker with a larger one.
 

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If you already have a fuse in your fuse box specifically for the Denali lights, then you don't need a second fuse inline.... I believe Denali provides the inline fues just in case you are running the lights directly to the battery... Curious, why 20amp a fuse? Is that what came with the D2s? Just seems excessive, since the D2s are only pulling less than 2 amps to operate (not more than 20 watts total)... I had the D1s, so I know the wiring is rated for higher amps... but I used 7.5 amp fuse on my D1s... Even a 5 amp fuse would have worked....
 

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I think the OP is asking if, instead of removing the inline fuse holder, he can just put in a fuse with a much higher rating to effectively "take it out of the loop". I don't see any harm in this, other than it's another potential failure point. If you don't need it, I'd remove it and connect the wires with some posi-locks and put a fuse with the correct rating in the fuse block.
 

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No wire downstream from a fuse can be smaller than the fuse is rated to feed.
 

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Discussion Starter #6
Curious, why 20amp a fuse? Is that what came with the D2s? Just seems excessive, since the D2s are only pulling less than 2 amps to operate (not more than 20 watts total)...
You got it! The 20A fuse came with the lights. In doing some additional research, I think it's there in case more lights are to be installed. Or something like that. :confused:
 

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Inserting a higher than required amperage fuse will turn the wiring harness into the fuse. "Fire Bad" Frankenstein
If I understand the OP correctly, he's still planning to run the correct fuse in the fuse block. He just doesn't want to remove the inline fuse holder so he's putting in a higher-rated fuse in the inline fuse holder. The fuse in the fuse panel will still protect the system.
 

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If I understand the OP correctly, he's still planning to run the correct fuse in the fuse block. He just doesn't want to remove the inline fuse holder so he's putting in a higher-rated fuse in the inline fuse holder. The fuse in the fuse panel will still protect the system.
From the OP:
Question 2

I'm aware there's a formula for determining the correct type of fuse for each component, but for the sake of curiosity, is there harm in putting a higher amp fuse than what's needed? For example, if something normally requires a 5A fuse, what would happen if I threw a 10A fuse in there?

Hence my response.

I also should mention to the OP that so long as the fuse position in the fuse box is rated at 20 amps and the aggregate fused amps does not exceed the amperage rating of the fuse box all should be fine with that configuration.
 

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FORUM GODFATHER.....R.I.P. PAT
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I'll say it once more. Do not use a fuse rated for more than any downstream wire can carry.
 

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Fair enough. You and I were answering different questions.



Out of curiosity, what would be the harm in, say, having a 5A fuse in the fuse block, and a 20A fuse in the inline fuse holder?
It's a waste of a good 20A fuse, fuse holder and a little space.
 

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Discussion Starter #14
Thanks, everyone!

I'm hoping I didn't start some kind of crazy debate on how to properly fuse accessories!

My intent is to simply remove the 20A fuse that's currently in the inline fuse holder and place it into the fuse box. I would be leaving the empty inline fuse holder in place, since it gives me the extra wiring run needed to reach the fuse box (otherwise, I'd have to cut off the inline fuse and connect a new wire - that sounds kinda dumb).
 

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An empty inline fuse holder will not pass current. Very few fuse blocks will handle 20A and are best fused no higher than the 10 or 15A they are rated for. One exception I'll make is for a Stebel horn that will very occasionally blow a 15A fuse though it is supposed to max out at 13A but is never on for more than a few seconds. I'll take a chance that the wires won't find that magic brush short that won't blow a 20A fuse but will draw more than 15A since my PC8 is rated for 15A fuses.
 

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Discussion Starter #16 (Edited)
An empty inline fuse holder will not pass current. Very few fuse blocks will handle 20A and are best fused no higher than the 10 or 15A they are rated for. One exception I'll make is for a Stebel horn that will very occasionally blow a 15A fuse though it is supposed to max out at 13A but is never on for more than a few seconds. I'll take a chance that the wires won't find that magic brush short that won't blow a 20A fuse but will draw more than 15A since my PC8 is rated for 15A fuses.
Thanks, grey! That's pretty much the answer I was looking for... I'll cut out the inline fuse holder (maybe I'll use it another time) and just connect additional wiring that matches the original. I think it's a 14ga wire, but I'll check it just to make sure. I'll match it up and go from there.

I'm also rethinking the mounting point of the fuse block. Since most of the stuff is in the front, I can try and find a way to mount it there. In reading the post from Johnofchar in VSI, which one of these Low Beam wires could I use to get switched power?

Low Beam - Black/Blue from fuse to light. White/Blue from switch to fuse.
 

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If you want the auxiliary lights controlled depending on hi/lo main beam choice, John has some good diagrams posted. I have a PC8 fuse block in the fairing on my bike. It has 3 10ga input wires for the main supply from ground, ignition on hot and always hot. From the fairing which has most of powered accessories, the output wires are shorter. Disconnecting the 3 input wires allows the PC8 to come off with the fairing. A Home Depot grounding rod clamp on the fairing frame hols an aluminum bar in place and the PC8 and an HID ballast are connected to the bar.

 

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I thought I could add some confusion to the OP's question...

I agree that the primary function of a fuse is the protect the downstream wire from over-current. However some devices recommend fusing to protect their own internal wiring or components. Many times a sensitive electronic device will have it's own fuse or internal protection. However sometimes they require an external fuse. In this case the fuse should be the size and type recommended by the device manufacturer, which will probably be much smaller than the fuse required to protect the chasis wiring.
 

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Discussion Starter #19
Congrats, dhally! You HAVE made it a tad more confusing! :hurray:

I realized that I really only have one or two other components that require a fuse. The USB charger from Burns Moto containts an automatic fuse, so I won't put any fuse in the box (unless others disagree). The Powerlet outlet is designed for 15A (according to the powerlet website).

The only other piece I need to worry about is the GPS, which from what I've read here could handle a 2.5A or 5A fuse. I'll have to do more digging to get the right size.

I'm also using a voltmeter and a switch for it. I don't believe I'll need a fuse for those, though I could throw in a small one for shits and giggles.
 

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Every hot wire on the bike needs a fuse as close to the power take off as possible to prevent that wire from starting a fire or destroying a wiring harness if that wire makes contact with ground.
 
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