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there is no better side of the circuit to fuse .
the commentary about which side is better is hair-splitting .
Triumph effectively fused the switch side and the ground side ... at different time periods
and even switched the polarity for the last few years of production .
( and fused each bike with only one fuse )

if you leave the fuse where it is ... its good ... and your work is done .
...your battery connections look cleaner than most

most mini fuse holders sold today come with red wires ... so this kind of defaults them to
Fusing the positive side to avoid ... wire convention confusion .
Whoever added your mini fuse was probably thinking along these lines .

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That's what I've got and that's what I'm keeping. Thanks to all. Like I said I do all my own work.


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There is a difference, which has been described many times.
It might seem to be a small (1%) difference, explain that 1% to the poor sod who just had his wiring melt (or much worse) because his seat pan, or something else, touched the live battery terminal. That is the 1% difference in security, 100% difference between fuse blowing or wiring burn-out.

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The sealed batteries I use are about 3/8" shorter than stock and the terminals are below the top of the battery. With a good strap the seat pan shorting out is pretty much impossible. That did happen to me a long time ago with a stock battery.


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It is the things we don’t allow for that take us by surprise.

Having the fuse on the live lead leaves that potential 1% surprise that we’re talking about.
Who knows that it’s just 1% anyway? It might be 10%, it might be 0.01%. That is the nature of chance and (sometimes) bad luck. Even 0.01% is only 1 in 10,000, 1% is 1 in 100.

If you could radically reduce the odds of bad luck by a simple change, would you not do it?
We adjust our lifestyles according to similar odds, to smoke, eat loads of burgers etc, and make choices depending on the importance we attach to these factors.

However, the choice of where to put the one and only fuse is a simple one, it requires no value judgement, merely logic.

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Logic prevails. I'll move the fuse over.


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...all new 125cc Japanese and patterns have the fuse on the hot wire. I do not know about new big bikes but I will check HD and Kawasaki soon; if I remember.
Triumph and most put the fuse in that wire in the late 70s.
Why they decided to not "protect" that 1%? May be they found severe problem could occurs not protecting the hot wire.
May be all these factories engineers were/are not so bright?

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Perhaps they thought they were stopping those pesky electrons from going anywhere by putting the fuse in the negative lead?
I once accidentally created a dead short across the battery while testing the charging system, the seat closed while I had large clips on the battery leads. That fried the common lead and in only a few seconds rendered the battery junk.
Would have been much better with the fuse in the common lead.


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Originally Posted by reverb
...all new 125cc Japanese and patterns have the fuse on the hot wire. I do not know about new big bikes but I will check HD and Kawasaki soon; if I remember.
Triumph and most put the fuse in that wire in the late 70s.
Why they decided to not "protect" that 1%? May be they found severe problem could occurs not protecting the hot wire.
May be all these factories engineers were/are not so bright?


More or less all new bikes have an electric start, which requires an unfused high current circuit.

The extra safeguard value of having the fuse in the return side is lost when there is a thick earth strap in parallel with the fused circuit.


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Originally Posted by koan58
It is the things we don’t allow for that take us by surprise.

Couldn't agree more. This year I re-wired my positive earth T100R moving the fuse from the negative battery terminal to the positive, all earth connections return to the fused single wire via a six way bullet sleeve. Pleased that everything worked when I'd completed the job I started to re-assemble the bike stupidly leaving the connected battery in place. I was tightening the seat restraining wire and dropped the spanner between the negative terminal and the frame resulting in a blown fuse. The original configuration wouldn't have protected me, at best I would've been examining the newly installed wiring for melted wires, it was my mistake but I can't guarantee that I won't make mistakes again.


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Originally Posted by koan58
It is the things we don’t allow for that take us by surprise.

Having the fuse on the live lead leaves that potential 1% surprise that we’re talking about.
Who knows that it’s just 1% anyway? It might be 10%, it might be 0.01%. That is the nature of chance and (sometimes) bad luck. Even 0.01% is only 1 in 10,000, 1% is 1 in 100.

If you could radically reduce the odds of bad luck by a simple change, would you not do it?
We adjust our lifestyles according to similar odds, to smoke, eat loads of burgers etc, and make choices depending on the importance we attach to these factors.

However, the choice of where to put the one and only fuse is a simple one, it requires no value judgement, merely logic.
Originally Posted by desco
Logic prevails. I'll move the fuse over.
Desco -- NO! He's telling you that logic says to put the fuse in the +ve return, just like you already have it on your bike. You don't need to change anything.

Also, this has come up at least once before CLICK


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...Mr Brasier; could you upload an image of those connectors? I am very interested. Thanks

-Still is unclear for me why Triumph and others decided to put in the hot wire the fuse in the late 70s

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Originally Posted by reverb
...Mr Brasier; could you upload an image of those connectors? I am very interested. Thanks

-Still is unclear for me why Triumph and others decided to put in the hot wire the fuse in the late 70s


Read the thread. Triumph moved the fuse to the live side in 1968.

It may have simplified production; maybe they expected to have electric start really soon!


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Rather than getting your knickers in a twist you could always put a fuse on each line.

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Originally Posted by Tridentman
Rather than getting your knickers in a twist you could always put a fuse on each line.

More connections in series means more opportunity for bad connections!


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-I just read this from Mr Healy:

"Now some of you will immediately recognize the problem and suggest that the fuse should have been put on the ground side of the battery. Well, in 1966 they did just that, but they discovered: if the fuse failed while the bike was running the bike would keep running and damage the rectifier. The next year they change the harness with the fuse on the feed side of the battery.
John"

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The flaws in that old post were pointed out years ago.

Whether the fuse is in the supply or return of the battery won’t make any difference to whether the engine continues to run after the fuse has blown.

When the fuse blows, the bike effectively reverts to a battery-less system.
Provided the charging system is reasonably efficient, a single-phase alternator with a 2MC capacitor will still allow the bike to run, as will a 3-phase alternator without the 2MC, without a battery (though starting may be more difficult).

I ran my bike for several years without a battery, it did not (and I see no reason why it should) harm the rectifier.

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Confusion reigns. Near as I can tell we are all talking about the same thing but calling them different names. For those of us that are pretty much ignorant when comes to electricity can we use + or positive terminal, - or negative terminal? Hot, live, supply, return, lead, ground,etc,etc. All I know is "positive earth" and that's the red wire.


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Originally Posted by desco
Confusion reigns. Near as I can tell we are all talking about the same thing but calling them different names. For those of us that are pretty much ignorant when comes to electricity can we use + or positive terminal, - or negative terminal? Hot, live, supply, return, lead, ground,etc,etc. All I know is "positive earth" and that's the red wire.


If you don’t understand live and return on a wiring diagram, do some studying until you do.


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Originally Posted by triton thrasher
Read the thread. Triumph moved the fuse to the live side in 1968.

It may have simplified production; maybe they expected to have electric start really soon!
That's why that stupid white/red wire started showing up in the left handlebar switch harness? If they really wanted to simplify production they would have left that unterminated until the starter was fitted.


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by the way

no matter where the fuse is its a good idea to cover the the top of the battery to protect it from the seat pan or a dropped bolt or whathaveyou

i cut a piece of inner tube that tucks neatly over the battery on my 72 under the strap and means that i never worry about what the terminals are doing under my fat ass


i'm old enough to remember when patriotism meant not trying to overthrow the government.
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