...Shouldn't this thing have more fuses?

[Tremelune]

I'm prepping to redo the wiring on my '68 CL350, and it looks like there is only one fuse on the bike. I've always read that you should fuse a wire whenever the gauge decreases...So if you have a fused 12 AWG wire run that splits into two 18 AWG runs, they should each be fused again.

Is the single fuse a product of the wild and dangerous 60s or is there something else I'm missing?

 

[Sonreir]

You information is incorrect. A single fuse works so long as the fuse is sized according to the smallest gauge wire in the circuit and the entire current draw of your circuit doesn't exceed that fuse.

 

[Tremelune]

So the tradeoff Honda made was to use a 15A fuse and 14 gauge (or thicker) wire everywhere to avoid putting fuses in a bunch of places?

Seems reasonable.

 

[hillsy]

GS450's only have 1 fuse.

Yep - just one.

 

[mydlyfkryzis]

So the tradeoff Honda made was to use a 15A fuse and 14 gauge (or thicker) wire everywhere to avoid putting fuses in a bunch of places?

Seems reasonable.

Not so much a tradeoff as a simple system. Small too...Think car...The wiring runs under the dash, front to rear, under the hood. More electrical accessories on the car..

A car has at least 8 amps in headlights, prolly 15 with all the tailights. The Heater motor is 10 amps all by itself. A car has a lot of high amp draw accessories. My Mazda Pick up has a 90 amp alternator...When antilocks are working, the whole car prolly has 60-70 amps of draw. You can't wire for 60 amps, so a car needs the circuits divided up more.

You 68 CL350 has an 9 amp alternator...when new. A 15 Amp fuse is adequate because your regular draw from the alternator won;t ever be higher then 15 amps. If you draw more, it's a short, and the battery is supplying it.....So 15A is fine....

And smaller wire would be more prone to breakage, so 14 Ga is good mechanically and electrically.

 

[Ichiban Moto]

If I use a single 15 amp fuse and 14 ga wire.. I can redo my bike with just that?

There are a bunch of wires going all over the place and at least 5 fuses now.

 

[Sonreir]

If I use a single 15 amp fuse and 14 ga wire.. I can redo my bike with just that?

There are a bunch of wires going all over the place and at least 5 fuses now.

Probably, but not definitely. It will depend on what needs power and how much power is needed. Most of the harnesses I make use a single 15A fuse, but you can't always go that route.

 

[Tremelune]

This whole site is excellent (if a bit janky):

http://www.bcae1.com/fuses.htm

 

[mydlyfkryzis]

If I use a single 15 amp fuse and 14 ga wire.. I can redo my bike with just that?

There are a bunch of wires going all over the place and at least 5 fuses now.

The advantage to extra fused circuits is that a short wont take out the whole bike. My cb360 has a main fuse then the lights on a separate fuse if my headlight shorted out, the bike would still run.

I prefer to divide circuits up. Easier troubleshooting too.


Sent from planet Earth using mysterious electronic devices and Tapatalk

 

[Rich Ard]

^ +1.

 

[ILoveThumpers]

Just my opinion...

At a minimum, in addition to the main fuse at the battery, there should be a fuse for lighting and a fuse for ignition.

If your bike has two circuits (one AC, for the headlight for instance and one DC for lighting) each of those circuits should have its own fuse.

I've seen too many dumb wiring problems kill off a perfectly good ignition module, which are expensive and getting harder to find.

-Deek

 

[mydlyfkryzis]

This whole site is excellent (if a bit janky):

http://www.bcae1.com/fuses.htm

Nice site. He missed on one point. Fuses do not protect downstream wiring or equipment. They blow because the downstream area has a fault. the Fuse/circuit Breaker protect UPSTREAM equipment. Headlight fuses, for instance, do not protect the headlight. They protect the battery and the wire upstream of the fuse from catching on fire and/or overloading the battery/alternator. The do protect the wire downstream as claimed, but not to keep wire safe, but to prevent a fire, that would ruin a car or a house or whatever.

Most people don't get that.

A stereo has a fuse to protect your wall wiring from catching on fire. Your circuit breaker upstream of the stereo protects the main breaker and circuit breaker box. The main breaker protects the electrical companies feed and transformer.

The stereo fuse, back to the website's claim, does not protect the stereo from damage. It already is damaged or it wouldn't have blown the fuse....However, it does protect your house and stereo cabinet, as it blows before the stereo can catch on fire (hopefully).

The rest of his reporting seems right....sizing, how they look when blown, etc. The premise that a fuse protects the end device is just not how it is designed. It is to prevent the wire from burning, and protect upstream electrical components.

 

[SONICJK]

Nice site. He missed on one point. Fuses do not protect downstream wiring or equipment. They blow because the downstream area has a fault. the Fuse/circuit Breaker protect UPSTREAM equipment. Headlight fuses, for instance, do not protect the headlight. They protect the battery and the wire upstream of the fuse from catching on fire and/or overloading the battery/alternator. The do protect the wire downstream as claimed, but not to keep wire safe, but to prevent a fire, that would ruin a car or a house or whatever.

Most people don't get that.

A stereo has a fuse to protect your wall wiring from catching on fire. Your circuit breaker upstream of the stereo protects the main breaker and circuit breaker box. The main breaker protects the electrical companies feed and transformer.

The stereo fuse, back to the website's claim, does not protect the stereo from damage. It already is damaged or it wouldn't have blown the fuse....However, it does protect your house and stereo cabinet, as it blows before the stereo can catch on fire (hopefully).

The rest of his reporting seems right....sizing, how they look when blown, etc. The premise that a fuse protects the end device is just not how it is designed. It is to prevent the wire from burning, and protect upstream electrical components.

The stereo fuse protects the stereo from damage if you screw up the wiring Which I believe is what he was saying. If you accidentally short something while wiring (say accidentally touch a hot wire to ground) the fuse will blow before (hopefully) any damage is done to the components.
I have tested this theory on amp installs several times. It gets close quarters, you accidentally touch the power and ground somewhere and POP there goes the fuse. Replace fuse and continue on your way.

Same works for motorcycles, if you accidentally short the wire going to your headlight, you pop the fuse instead of the 50 dollar sealed beam 8)

 

[mydlyfkryzis]

You cannot pop the headlight by shorting it....You can either put the 12V feed to ground ....which pops the fuse to protect the wire from burning and battery from exploding, or you ground the ground side........nothing happens.....

Stereo is different....But most of the stereo components already have internal, self resetting connections. If you short my stereo's output, you get an error code, wait till it cools down, and it resets itself......The fuse on my Stereo is only 5 amp....That allows over 500 watt. But you can have much more amps on the output....voltage is lower. On Auto's, the input and output voltages are closer, so you need higher input amps, so it fogs the idea that the fuse is upstream protection....But it is.

Of course, car amplifiers are a little different, but you are still protecting upstream...... There is a chance you kill the amp even if you pop the fuse.....But sized right, no chance of setting the wire on fire......The fact that the stereo is protected is actually incidental. I have been involved in UL approval on equipment at work, and the emphasis on this is fire prevention and upstream prevention. UL does not care if your stereo burns out, as long as it soens't set the wiring on fire, or cause damage "outside the box"".....

Edit: Some Stereo Amps have output fuses...They protect the amplifier (upstream), not the speaker, in case you short the output speaker wires....