Apropos of the recent thread on wire nutting stranded with solid, are there
any inherent advantages of one over the other? #14-#10.
Stranded is more flexible, an advantage if you have to pull long runs in
bends in EMT, but I find it a pain when connecting outlets, etc.
Stranded can be dicey-er with nicks, missing strands.
But, stranded might give more contact area under screws, in breakers, etc.
At HD, stranded is $5 more on 500 ft coil of 14 and 12: $25 to $30, and $40
BX/romex comes which way? Both?
Who uses what and when?
The contact area of solid wire under the screw will be several times
the cross-sectional area of the wire. Nothing to be gained from more
contact area than that. Stranded also has a tendency to squeeze out
from under the screw and loosen up.
Other than that, I think you covered most of it.
I don't recall solid conductors in an automobile. Stranded wire is less
subject to metal fatigue from bending or vibration. The smaller a
conductor is, the farther it can flex without bending the metal.
Stuff with 7 or 19 strands is usually classified as Rigid Stranded Wire.
Flexible Stranded Wire usually has 49 strands or more. I'd hate to try
to connect the flexible stuff with a wire nut. Until recently, the NEC
required crimping for it. Now there's an approved screw terminal.
In residential applications -- nonsense.
First of all, the NEC doesn't make a distinction between solid and stranded in
the limits it places on the ampacity of a conductor. The only factor is size.
Second, presumably you're referring to the "skin effect" -- which at 60Hz is
completely negligible. The frequency needs to be a *lot* higher than that
before there's any noticeable effect.
I was going to bring this up as well.
It depends on how the NEC defines gauge of a wire.
If it accurately sums the cross sectional area of each strand, so that this
sum is equal to the CSA of solid, then the ampacity should be very nearly
equal. But the diameter of the stranded would be slightly bigger -- because
of the inherent inefficient of "packing circles" -- ie, gaps between
non-touching parts of a circle.
If the NEC determines gauge based on diameter, then stranded will have less
ampacity than solid, for the same circle-packing reason -- less net CSA of
So, how DOES the NEC define "gauge"?
No one mentioned the fact that stranded wire, at the same diameter,
can carry more current.
And you could tin the ends of stranded for termination.
Tinning the ends of stranded is an excellent idea -- proly no one does it,
Just the ends?
When attaching line-cord (ordinary wire for lamps, etc) to those
two screws, to keep the strands from coming "loose" and maybe
shorting on the other side, I of course twist it tight, but then
tin the end, before wrapping the end around the screw and tightening
Anything wrong with doing that?
Please say more.
Wiring a lamp socket, tinning just the last 1/4th or 1/8th of an
inch, just to keep the strands from sticking out from where screwed
down, surely that's ok?
And being screwed down hard, no flexing, I'd hope.
Seems to me that a strand coming loose within airplane wiring
would be a lot more dangerous than tinning just a tiny bit
at the end to keep a strand from sticking out, with who knows what
Now, I am willing to be educated. Please don't just dictate
the correct answer, but try to CONVINCE us via argument,
data, metallurgy, whatever.
Worked at wiring broadcast studios, and we were not allowed to tin stranded
It was said that solder is too soft, and after tightening down screws or
clamps, the solder would just compress,
and would eventually cause a loose connection.
By doing so you take away flexibility of the stranded wire so right at
your connection it is more likely to fail. As much as I hate crimped on
wire connectors and always believed soldered was better than connectors,
where there is a lot of vibration they do last much longer than soldered
on wires. Can someone check with NASA?
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