Bus Bar Design--Why Twist copper Wire?


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Riplash

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Joined
May 27, 2018
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71
Hey All,

I have a question about why a lot of powerwall builders twist 10 AWG or 12 AWG copper wire together to make their bus bars. Is it cheaper that way, or does that allow you to use wire you already have? What are the advantages and disadvantages of twisting the smaller wire as opposed to buying 8, 6, or 4 AWG solid bare wire?

-Ryan
 

Korishan

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Jan 7, 2017
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It's usually a lot cheaper as the 10/12/14 is more common for house hold electrical. 8/6/4 is a bit more expensive. Also, the larger it is, the harder it is bend. And when the thicker copper is bent, it could cause hot spots during heavy current draw on the outside of the bends; though, I don't think others have really thought about this particular issue.

14/12/10 can even be readily found around construction/renovation sites as scrap. Could probably even find lots of it at the recycler/junkyard.
 
Joined
Dec 8, 2017
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Yeah, go to google images, or any large hardware store and search "Romex 3-wire cable". If you talk nice to demolition crews, they might let you harvest a LOT of that out of the rubble when a house is knocked down (some salvagers don't ask, and just go before or after work).

If the free/near-free wire you harvest is big enough, you're set. If it is a little small, just double up on it. If you have tons of it, I think the general attitude is "even if I don't need to doubleit, why not?".

If you decide to double the thickness of what you have, twisting is just a convenient method, no secret reason for that style.
 
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Mar 7, 2018
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+1 for the free wire from re-wires/demolition, copper does not age like the insulation.... When twisting wire and it is more than 7 strands then double twist like with steel wire cabling as this will give a more structured / consistent result. Very long strands, just use an electric drill - I have done upto about 100ft and gets a bit challenging as it needs to be only supported at each end....
 

Riplash

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Joined
May 27, 2018
Messages
71
I was pretty sure that was the reason, but I wanted to be sure. I can barter at the scrapshop, and can trade one type of metal that I sell for othersfor so I have access to all sizes of copper wire and stuff.SoI will use whatever works best for me forthe project.

I also use insulated strips of 14, 12, and 10 AWG solid wire as tie wraps that are alot cheaper than the premade tie all wraps that you can buy at the store.

Cheers,
Ryan


image_xvlmbo.jpg
 

marcin

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Dec 25, 2017
Messages
42
I took deferent approach to bus bar wiring.
1) it is less expensive to use scrap or existing wiring.
2) allows for easy replace of bad cell from pack
3) requires less heat/time to solder
Entire pack is soldered within 1.5 hour using 30 Watts soldering iron


image_dknaov.jpg
 

Korishan

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4) Looks really kewl ;)
 

Loquist

New member
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Jul 20, 2018
Messages
27
marcin said:
I took deferent approach to bus bar wiring.
1) it is less expensive to use scrap or existing wiring.
2) allows for easy replace of bad cell from pack
3) requires less heat/time to solder
Entire pack is soldered within 1.5 hour using 30 Watts soldering iron


image_dknaov.jpg

What gauge wire are you using for the secondary (smaller) busbars?
 

Loquist

New member
Joined
Jul 20, 2018
Messages
27
marcin said:
I took deferent approach to bus bar wiring.
1) it is less expensive to use scrap or existing wiring.
2) allows for easy replace of bad cell from pack
3) requires less heat/time to solder
Entire pack is soldered within 1.5 hour using 30 Watts soldering iron


image_dknaov.jpg

What gauge wire are you using for the secondary (smaller) busbars?
 
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