Stranded Or Solid (and Why) - Electrical - Contractor Talk

Stranded Or Solid (and Why)

 
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Old 12-26-2009, 07:47 PM   #1
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Stranded Or Solid (and Why)


I brought the EC who originally trained me into a job recently for his manpower etc. He is now using stranded 12 & 14 where he used to hate it. We always used solid 12 & 14 when I worked for him years ago.

I respect him but his reasoning for the switch was unclear to me. (He wasn't even really sure, they just switched over the years)

Here are my perceived pro's with stranded vs: solid (12 & 14 only)

Solid
Stays aligned on spools better (less "knots")
Easier to terminate on devices (no rogue strands to worry about)
Much neater service panel work
Twisting terminations more solid (no pun intended)
Easier to push through greenfield for whips

Stranded
Easier to press larger devices like GFCI's and dimmers into boxes
Smoother pulls on long home runs

I'm curious what your experiences are.

EDIT-I neglected to mention that all work in my areas is required to be in conduit. We can't use romex at all. (Thanks Woodchuck)
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Old 12-26-2009, 08:13 PM   #2
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Re: Stranded Or Solid (and Why)


12 and smaller, solid unless specs or manufacturer dictates otherwise.

10 and larger, stranded if at all possible.

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Old 12-26-2009, 08:35 PM   #3
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Re: Stranded Or Solid (and Why)


For me it depends on the job and what requirements are agreed upon. Anything in EMT/Conduit is stranded but most other work is solid wire. I do however like to use Ideal Pigtails for most connections as they are 12ga stranded copper with a forked connector so the connections can be pushed into the back of the box and there is less stress on the device.
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Old 12-26-2009, 08:38 PM   #4
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Re: Stranded Or Solid (and Why)


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Originally Posted by woodchuck2 View Post
For me it depends on the job and what requirements are agreed upon. Anything in EMT/Conduit is stranded but most other work is solid wire. I do however like to use Ideal Pigtails for most connections as they are 12ga stranded copper with a forked connector so the connections can be pushed into the back of the box and there is less stress on the device.
Thanks woodchuck. I guess I should have mentioned that in my area, all work is required to be in EMT. I'm going to edit the OP to reflect that.
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Old 12-27-2009, 12:03 AM   #5
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Re: Stranded Or Solid (and Why)


Stranded is certainly easier to pull.

Electrically, there's some theory I learned decades ago--and don't know if it's been disproven or not--that says electrical current tends to travel mostly on the "skin" of a conductor. If that's truly the case, stranded would provide much more surface area for that flow and therefore be significantly more efficient.
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Old 12-27-2009, 07:40 AM   #6
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Re: Stranded Or Solid (and Why)


Great Question ! Having worked in Industry for many years-we used mostly all stranded wire & cable. Some advantages are it is much easier to pull in cable trays & conduit. It also seems to have a much tougher covering on it, unlike solid which cuts so easily. Another is a strands can be broken off & the rest are still there to conduct. On solid they break off completely & you lose connection,
On the downside stranded cable is much harder to strip. The conductors don't wrap around screws good, but we always used crimped connectors on them which IMO is even better. Another downside is a strand can be sticking out of where it should not & cause problems down the road- like one sticking out of a wire nut-which I have gotten a few shocks from........ Time for breakfast- hopefully we get more input..................
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Old 12-27-2009, 08:17 AM   #7
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Re: Stranded Or Solid (and Why)


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Stranded is certainly easier to pull.

Electrically, there's some theory I learned decades ago--and don't know if it's been disproven or not--that says electrical current tends to travel mostly on the "skin" of a conductor. If that's truly the case, stranded would provide much more surface area for that flow and therefore be significantly more efficient.
Absolutely true.
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Old 12-27-2009, 08:54 AM   #8
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Re: Stranded Or Solid (and Why)


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Absolutely true.

And this is why, when you drive by and look at an electrical substation, many of the conductors look like pipes.

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Old 12-27-2009, 10:08 AM   #9
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Re: Stranded Or Solid (and Why)


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And this is why, when you drive by and look at an electrical substation, many of the conductors look like pipes.

Good point. I do not think it is necessary to involve physics when discussing wires. The if the UL and NEMA consider a wire as sufficient to carry a load, that's OK with me.

In real numbers, what is the ampacity difference from say, 12 solid and 12 stranded? Pretty small I would guess
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Old 12-27-2009, 10:42 AM   #10
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Re: Stranded Or Solid (and Why)


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Good point. I do not think it is necessary to involve physics when discussing wires. The if the UL and NEMA consider a wire as sufficient to carry a load, that's OK with me. ........
Well then, let's throw Ohm's Law out the window.........
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Old 12-27-2009, 10:50 AM   #11
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Re: Stranded Or Solid (and Why)


My point is as far as conductors, there is no real difference between solid and stranded. It becomes more of a preference for the behavior of the wire as a working meduim. By that I mean pulling, stripping, connecting, and the longeviety of connections.
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Old 12-27-2009, 03:46 PM   #12
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Re: Stranded Or Solid (and Why)


on machinery, or places with a lot of mechanical stuff and vibrations we've always used stranded with crimp on connectors.



I used to work with a company wiring premade MCC control towers and stuff for gravel pits and tar sands, that were shipped in sections and reconnected on site. We used mostly all stranded and connectors like that in the buildings.

For the control circuits they were solid wire but they were all going into terminal blocks, relays, fuse holders etc.

95% of all other work I ever did (mostly residential) has been solid.

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Old 12-27-2009, 06:09 PM   #13
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Re: Stranded Or Solid (and Why)


Interesting replies. Especially about the skinning effect.
Common sense would tell me that the electrons would "skin" to the outermost surface. (Including the assembly of all combined strands, thus making stranded and solid about the same)

Am I wrong?

It looks at this point that I am going to stick with solid 14's & 12's.
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Old 12-27-2009, 06:23 PM   #14
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Re: Stranded Or Solid (and Why)


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Originally Posted by rselectric1 View Post
Interesting replies. Especially about the skinning effect.
Common sense would tell me that the electrons would "skin" to the outermost surface. (Including the assembly of all combined strands, thus making stranded and solid about the same)

Am I wrong?

It looks at this point that I am going to stick with solid 14's & 12's.

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Old 12-27-2009, 06:25 PM   #15
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Re: Stranded Or Solid (and Why)


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Why is there an ad in your post?
?-The dremel ad? or am I missing something else. (I usually am)
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Old 12-27-2009, 08:59 PM   #16
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Re: Stranded Or Solid (and Why)


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Common sense would tell me that the electrons would "skin" to the outermost surface. (Including the assembly of all combined strands, thus making stranded and solid about the same)
Well, anal-ytically, that's the outermost surface of a solid conductor. Stranded wire consists of several solid conductors, which at the atomic level are miles apart except at the ends where they're crimped or otherwise compressed together.

So in theory, the [majority of] current travel takes place in parallel, on the surfaces of all the conductors.

But Anti is right; you'd most likely never really notice the difference in efficiency between stranded and solid outside of a lab. So it basically comes down to whatever's most comfortable for you to work with.

For me, that would be stranded any time I have to deal with pulling the stuff through conduit, if there are any elbows at all involved. I'll gladly trade some fussiness at the terminations for less gruntin' & cussin' during the pull.
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Old 12-27-2009, 09:18 PM   #17
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Re: Stranded Or Solid (and Why)


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?-The dremel ad? or am I missing something else. (I usually am)

Your SmileyCentral link. I think you copied the URL of the website itself and not the smiley you wanted.
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Old 12-27-2009, 11:01 PM   #18
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Re: Stranded Or Solid (and Why)


For 12-14AWG might want to read the devices you you use... most screw terminals are not aproved for stranded and specifically "state solid wire only"
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Old 12-29-2009, 03:55 AM   #19
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Re: Stranded Or Solid (and Why)


Whoa, i think this solid vs stranded and the skin effect is headed down the wrong path in a hurry. Yes there is a skin effect, some electricity also flows through the core of the wire. 14ga solid and 14ga stranded THHN are rated for exactly the same current capacity. stranded wire is just thinner overall and more flexable. We're not throwing ohm's law anywhere, it's already been figured out

AWG as it is orginally defined relates to solid wire only. look up "American Wire Gauge on Wikipedia"





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Old 12-30-2009, 01:21 PM   #20
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Re: Stranded Or Solid (and Why)


Is there not a price difference between the two? I always thought stranded was more expensive. In commercial and industrial work, we always used stranded. Its alot easier to pull 7 #12 strandeds through a 1/2 pipe than solid thhn.

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