# Electro-phob... or these ain't My druthers



## Totalwrecker (Feb 26, 2009)

Too basic for here, but fortunately I now have a clue!







, but not a Fool-proof validation! Lordy knows that's the kind I need the most!

On my first install, I thought I was on top of it all and still blue smoked my prize...







, one replaced brain later I think it's ready. Wish it was mine...oh well.

So here I am in the middle of #2 install and aprehensions have made me easily distracted







, yes too easy as many of you wonder aloud as; am I 'still' working on that









If I've learned from all my mistakes I must be brilliant! A glimmer as been reached as I added a 3 amp fuse to this install. Will wonders never cease? And now the question.

Does it matter on which side of the circuit it gets installed?

I tried 'search' and my one clue was one poster said he put it on the + side and nobody corrected that. Is this correct?

I made my own fuse holder using 3 amp auto blade fuses and a couple RS female quick Disconects. Instead of crimpimg I reshaped it to wrap around the wire and I soldered it in. Then I bent them 90 degrees, located a clear area above and drilled 2 holes through the tender floor. With the connectors on I glued them in place on the underside of the tender floor. First holes and after that set I removed the fuse and epoxied support for the bent ends. Now when she stops all I need do is flip the tender over to see if that's the problem. 

I hope this entertained as I feel semi-silly asking such a basic thing....









John


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## dbodnar (Jan 2, 2008)

Posted By Totalwrecker on 30 Nov 2010 11:34 AM 
Too basic for here, but fortunately I now have a clue!







, but not a Fool-proof validation! Lordy knows that's the kind I need the most!

On my first install, I thought I was on top of it all and still blue smoked my prize...







, one replaced brain later I think it's ready. Wish it was mine...oh well.

So here I am in the middle of #2 install and aprehensions have made me easily distracted







, yes too easy as many of you wonder aloud as; am I 'still' working on that









If I've learned from all my mistakes I must be brilliant! A glimmer as been reached as I added a 3 amp fuse to this install. Will wonders never cease? And now the question.

Does it matter on which side of the circuit it gets installed?

I tried 'search' and my one clue was one poster said he put it on the + side and nobody corrected that. Is this correct?

I made my own fuse holder using 3 amp auto blade fuses and a couple RS female quick Disconects. Instead of crimpimg I reshaped it to wrap around the wire and I soldered it in. Then I bent them 90 degrees, located a clear area above and drilled 2 holes through the tender floor. With the connectors on I glued them in place on the underside of the tender floor. First holes and after that set I removed the fuse and epoxied support for the bent ends. Now when she stops all I need do is flip the tender over to see if that's the problem. 

I hope this entertained as I feel semi-silly asking such a basic thing....









John


John - if you are asking if you should install the fuse on the positive lead or the negative lead it makes no difference. Traditionally fuses are put onto the positive lead but either one carries the same load and will blow the fuse.

dave


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## Michael Glavin (Jan 2, 2009)

Dave, 

Me thinks John is asking weather to install the fuse on the supply voltage or the load/motor side of things... I'd suggest installing the fuse on the power source or inlet into the device, isolating the power source from the device to protect all in the event of smoke letting.

Michael


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## dbodnar (Jan 2, 2008)

Posted By Michael Glavin on 30 Nov 2010 12:42 PM 
Dave, 

Me thinks John is asking weather to install the fuse on the supply voltage or the load/motor side of things... I'd suggest installing the fuse on the power into the device, isolating the power source from the device to protect all in the event of smoke letting.

Michael If that is the case, Michael, there is no question that the fuse should be close to the battery or power supply..... doesn't do much good if something shorts before the fuse!

dave


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## Michael Glavin (Jan 2, 2009)

Dave, 

You know I missed the "+ side" comment on first gander, perhaps you were spot on! My bad. 

Michael


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## Semper Vaporo (Jan 2, 2008)

From an electrical point of view, it doesn't matter where the fuse is in a circuit. Current flow in a series of components is the same at all points from the power source back to the power source, so if the current exceeds the rating of the fuse, it overheats and burns to the point of breaking the electrical continuity and the flow of current ceases.

There are other reasons to put a fuse in certain places. Those reasons take into consideration the physical relationship of the parts in the circuit, but normally you want the fuse close to the power source so that any accidental short is still on the away side of the circuitry.

1) What are you wanting to protect with the fuse?
2) What are the reasons it needs protection.
3) What causes the need for protection?

You want to protect people and you want to protect the device itself.

It needs protection because it might catch fire if too much current flows, or it is expensive to replace, or a person might get hurt.

The causes for the need might be other components that might fail and allow too much current to flow, or an external event might cause wires to contact each other thus bypassing components that limit the current flow and thus allows too much to flow or puts current in places that might harm other components or might harm property or people.

In a battery circuit, it doesn't matter whether the fuse is on the "+" side or the "-" side. but it should be as physically close to the battery as possible... as in; 

Battery pole --- fuse --- power wire to the circuit --- the circuit components --- power wire back to the opposite battery pole; or 

Battery pole --- power wire to the circuit --- the circuit components --- power wire back to the fuse --- the opposite battery pole.

If the power source has multiple paths from each pole then the fuse should be in the side with the fewest paths (multiple fuses if multiple paths). I mention this to point out that in AC "House Power" one side is designated the "Hot" side and the other is physically connected to the "Earth" (dirt, the World, etc.) and is designated the "Ground" side. The Ground side can have multiple paths that are difficult to control (like paths through water pipes, furnace ducts, YOU standing on the ground or anything that is in electrical connection to the ground. The fuse must go on the side that is easiest to control electrical connections and that is the "Hot" side... One wire out to multiple sockets for components to use the power and then one wire back, but that wire back is the same as any place on the earth and is only there to provide a reliable electrical connection (the earth is non-uniform in conductivity and would play havoc with most components using the power). The fuse should be in the head end of the wire OUT to the sockets.

Traditionally, in automotive battery circuits the negative ("-") side of the battery is connected to the chassis and is considered "Ground" and individual circuits for lights, etc. are connected through fuses to the positive ("+") side, thus the fuses are in the "+" side, but if there were just one fuse for the whole shebang it could go in either side and be equally protective.


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## Totalwrecker (Feb 26, 2009)

Thanks guys, 
I was on the simple side here. Just polarity. 
On this install, there is a battery car and the fuse is tender bound on the power 'in line', post track or battery power DPDT, pre circuitboards. 

I'm hpoing to dot my i's before before the smoke this time. 

Thanks again, 
John


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