Adding a fuse to lights and horn feeds

29er

29er

Senior Member
A couple of threads ago we discussed the use of a 30 amp breaker (or fuse) at the starter:

http://www.fordbarn.com/forum/showthread.php?t=160715&highlight=breaker

A few of you discussed the value of additional breakers (or fuses), especially at the light and horn feeds ;) .

This seems like a really good idea because while on a drive today my coupe suddenly died at an intersection just as I signaled a turn :o . I quickly found and repaired a short in a lighting wire. If that feed had a fuse, it would have blown, and the car would not have stalled (the short blew the fuse at the starter and the car died :( ).

I'm thinking of adding separate breakers to the lighting and horn feeds in addition to the one I have at the starter.

This should be pretty easy and I have a couple of ideas of HOW to do it, but would be enlightened to learn how others have accomplished this, and especially how to make it tidy and look professional.

So if you've done this and are game to pass along your experience, pictures are always helpful. A list of specific parts that you used would also be beneficial. The more specific the better. :)

Perhaps this has already been discussed on the Barn or in a magazine somewhere? :confused: If so, a reference or link would be great.

Thanks in advance for your ideas! :cool:

Mike
 
I have one A with two ATC/ATM mini fuse holders to the horn and lights. I used the clear holders, as I use the 'indicating' type fuses. I also have a 40A breaker directly on the output lug of the Denso 3-wire alternator.
DensoAlternator.jpg

The clear holders look like this:
46278FL.gif

If you don't care about indicating fuses, just use the standard inline black ones. Some canvas loom cover and friction tape sorta-kinda makes it look better than a rat's nest.
 
Mike: Thanks much. Yes, it is INDEED a tidy job!

I did a little search and found a source on Amazon for the indicator-type blade fuses, called "Blo-n-Glo" or "Smart-Glow" as well as the holders for these:

http://www.amazon.com/s/?tag=atomicindus08-20

Will these fuses work for 6 volt?

The indicator-type fuses would be convenient.

I see you have separate fuses for the lights and horn, which seems a great idea.
 
Hey P.S.

Thanks! What feeds exactly do you have fuses on? I see 3 fuse holders in addition to the fuse on the starter. I'm guessing the fuse on the line coming from the starter is to the flasher? The other two are for horn and lights?

Looks nice and easy to access!

Mike
 
OL JENNY said:
Mike, where do you find the clear holders?
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I got everything from Waytek. Warning! They have a nice online page-flip catalog. Once you start flippin' you'll end up with $50 more stuff than you were looking for.

Here's the holders, they take the mini fuses, not the full size. LINK

Here are the indicating fuses:LINK You can also find the indicating fuses (both full and mini size) in most parts stores.

29er said:
Will these fuses work for 6 volt? The indicator-type fuses would be convenient.
Click to expand...
I don't know if they will light bright enough when blown on 6V. Since the fuses contain reverse-paralleled LED's with a ballast resistor they would probably light, but at reduced intensity, on 6V. If you understand electronics/LED characteristics there are two reverse-parallel LED's in them so they work with current flow in either direction. The 6V is over the forward voltage rating of most LED's and there is no series progression of LED's, so my best guess is yes on 6V, but at reduced intensity- not exactly half, as you need to subtract the forward LED threshold voltage from your supply voltage and then figure current with the internal series ballast resistor (yea, too much information!) You could just buy one at your local parts store and put it directly across a 6V battery to try it. That will blow it instantly and it should light.

Keep in mind they only illuminate when the circuit is "ON" and there is a short or overload. Example: Short in headlamp bucket: fuse blows, fuse lights IF light switch is ON. If you turn off the light switch the fuse will not illuminate even though it is blown and there is a short in the lamp.
 
CIRCUIT BREAKER !!!!!!!!! NEVER, that is unless you want to destroy an exhaust system. I blew out a $300 stainless muffler.
The ckt opened up ling enough to fill the exhaust with fuel and then ignition and a large explosion.
Fuse is the only way if you must. I personally fust all my cket with the plug in blade fuses shown above and leave the ignition alone. That has enough issues on the road without adding that.
Jim G.
 
James G. said:
CIRCUIT BREAKER !!!!!!!!! NEVER, that is unless you want to destroy an exhaust system. I blew out a $300 stainless muffler.
The ckt opened up ling enough to fill the exhaust with fuel and then ignition and a large explosion.
Fuse is the only way if you must. I personally fust all my cket with the plug in blade fuses shown above and leave the ignition alone. That has enough issues on the road without adding that.
Jim G.
Click to expand...

Interesting event. FWIW, there are two general kinds of circuit breakers- manual and auto-resetting. You must have made the mistake of using an auto-resetting breaker.
 
I would be very carful about fusing / breakering the output of a alternator or generator. If the link opens up the generator / alternator will lose the battery which works as a load and the voltage will go very high possibly damaging the generator, or alternator. I like fuses or breakers, just not on the wire that connects the generator to the battery.
 
29er said:
Hey P.S.

Thanks! What feeds exactly do you have fuses on? I see 3 fuse holders in addition to the fuse on the starter. I'm guessing the fuse on the line coming from the starter is to the flasher? The other two are for horn and lights?

Looks nice and easy to access!

Mike
Click to expand...

Yes, the third fuse holder is for the turn signals and emergency flashers.

I run a 40 amp fuse on the main. The starter mounted fuse holder has since been changed to a firewall mounted inline watertight fuse holder (using existing hole).
 
I don't know if they will light bright enough when blown on 6V. You could just buy one at your local parts store and put it directly across a 6V battery to try it. [I said:
That will blow it instantly[/I] and it should light.
Click to expand...

Mike: I accepted the challenge and here's what I discovered:

I bought a 25amp "Smart Glow Fuse" and wired it to a 6v battery. As soon as I completed the circuit by connecting it to the positive battery post, the fuse blew and immediately lit the LED indicator (red).

The LED indicator was VERY bright and EASILY seen, even in direct sunlight.

Conclusion: The 12v indicator fuses do work in a 6v system and provide a convenient method to detect a blown fuse.

Thanks to all who offered comments and photos of your set-up.

I'm still mulling what I'll do, but am leaning away from the circuit breakers because I didn't see one that indicated when it was tripped. The indicator fuses are a little more expensive than the tubular glass ones, but are easier to tell whether they've been blown. I like that. Finally, I'm leaning towards installing separate fuses on the following feeds: (1) horn; (2) flasher (turn signals); and (3) headlights & tail lights.

Thanks!

Mike

PS. Just for future reference, here's an old thread on the subject of fuses:

http://www.fordbarn.com/forum/showthread.php?t=94885&highlight=fuse+for+horn
 
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