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The truth about wire, fusing and voltage drop!


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I'm a certified technician in plc and electrical systems.

I've spent over 20 years building testing installing and designing electrical power distribution and control systems from floating offshore rings to power plants.

 

I want to start with a simple topic. That's debated and I'm just down-right tired of the misconceptions.

 

STRAND COUNT- Higher strand means lower resistance in the same gauge and results in higher ampacity(how much current can flow for a given voltage drop).

 

This is completely false. Soil wire of the same circular mill vs high strand count will have both less resistance and higher ampacity. 

 

Think about this. Why would 200,000$

Industrial load centers waste time with solid busbar and not just use heavy jacketed high strand wire? 

 

3 apparent reasons. Termination and ampacity heat dissipation.

 

Termination meaning you get the best contact area and you can get consistent torqued connections.  This is VERY important in long term connections where thermal expansion occurs.

 

2 solid busbars have considerably higher ampacity. The election flow flows much better in solids.

 

3 dissipation, the bars are exposed to air and any cooling installed rids the heat substantially faster. 

 

 Strand count is only advantage is flexibility.  If you have a 1/0 wire that has a 200 strand count(thhn) it's circular mill is 325 to meet the nec standard of 1/0 wire.

   Welding wire has near 3000 strands and in order to meet the same standard needs to be nearly 400 circular mill.

 Same for car audio wire. It needs to be neat 450 circular mill.  So knowing that now you understand why welding cable 2/0 fits into car audio 1/0.

 

Fyl weling cable 2/0 will carry about 40 mores amps over the same distance with the same voltage drop.

 

Gonna keep this short and sweet. Fusing is for safety. It is not over current protection. You fuse to the maximum ampacity of your wire and you wire for 125% of you loads ampacity. Do this and you will never have issues. 

 

Voltage drop is defined buy the wires resistance and the current in the circuit.  It's that easy. 

Also in a DC circuit the length of both the ground and power wire are factored in. 4ft power and 3 foot ground is 7ft. 

 

 

Edited by bassfreak85
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I really want to understand this completely, excuse me if these are dumb questions. 

What is circular mill? Is that another term for a buss bar? 

My cable I'm using is something like 5400+ strands of OFC copper. Considered 1/0 in, for lack of a better term, "car audio terms". It always kind of seems to me that welding cable, where it is pure copper, to carry the same amperage as my 1/0, if need 2/0 awg welding cable. 

And voltage drop is defined by the wires resistance and the current in the system. I get that, so the current of the system=battery+alternator right? And the resistance would be coming from the wire used. 

If you answer, I probably will have follow up questions because I enjoy talking car electrical distribution for some odd reason

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2011 Chevy Silverado under construction

My build log here. Check it out! 

 

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I'm curious if there are specific specs/standards for strand-size or if it's the wild west.  It has been my experience that not all 1/0 (or any gauge) is created equal.  Brands like Sky High and KnuKonceptz have high "strand counts" but also deliver (visibly noticeable) more copper, not just more stands of thinner copper.  I've watched some manufacturing videos on how they extrude/stretch the strands, just curious if/what standards or classifications exist. 

 

Thanks for starting the thread bassfreak85.

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6 hours ago, Arthur79 said:

I'm curious if there are specific specs/standards for strand-size or if it's the wild west.  It has been my experience that not all 1/0 (or any gauge) is created equal.  Brands like Sky High and KnuKonceptz have high "strand counts" but also deliver (visibly noticeable) more copper, not just more stands of thinner copper.  I've watched some manufacturing videos on how they extrude/stretch the strands, just curious if/what standards or classifications exist. 

 

Thanks for starting the thread bassfreak85.

It's my understanding that there really is only the American Wire Gauge size as far as an industry standard, but it is sort of the wild west when it comes to strand count. As far as car audio cable goes, it actually way exceeds AWG as far as size goes as well. The only way to move more amperage more efficiently, and beat out your competitors wire, is more copper which equals bigger cable.... but they still call it 1/0.

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2011 Chevy Silverado under construction

My build log here. Check it out! 

 

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16 hours ago, Arthur79 said:

I'm curious if there are specific specs/standards for strand-size or if it's the wild west.  It has been my experience that not all 1/0 (or any gauge) is created equal.  Brands like Sky High and KnuKonceptz have high "strand counts" but also deliver (visibly noticeable) more copper, not just more stands of thinner copper.  I've watched some manufacturing videos on how they extrude/stretch the strands, just curious if/what standards or classifications exist. 

 

Thanks for starting the thread bassfreak85.

You have to understand that weight means nothing. The actual purity of the copper and jacket are very critical.

 

Look at this chart. 

 

http://www.armstrongssupply.com/wire_chart.htm

 

If the wire isn't UL listed I don't car the weight size of circular mill. UL listed wire meets the standards on premium insulation and dissipation properties and true OFC copper.

 

Just cuz it's says ofc does mean it's not Chinese recycled copper. Lol

Basically weight and size don't mean much what you want to know is resistance near the wire therminal limit. 

 

Like measuring power compression on a voice coil for example.

 

 

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