Can some of you elloborate on the differences between solid condutor and stranded wire for typical installations like lites?? emf, counter emf, right hand rule, inductive reactance, voltage drop, eddie currents, harmonic currents. What's the princaple behind solid over starnded?

i saw a trade mag ad advocating solid.....did'nt get into detail.....

Stranded is easier to pull into conduit (especially long runs), more resistant to vibration. Harder to use with device terminals (need crimp lugs or pressure plate terminals) and wirenuts.

Solid is a bit cheaper for some reason. Easier to connect properly, though.

I agree stranded wire is much easier to pull and solid wire is better at terminations. But how the current flows is more what I was asking. Does the current runs, through the core of the conductor, so a solid wire would have less resistance as apposed to stranded. HOw does this apply to our everday applications of multiple lighte tied in, like floresent. I see specs call for solid wire applications where ther is a lot of lights installed.

[This message has been edited by Wirenuttt (edited 12-12-2002).]

Current flows on the surface of the conductor. Standed has more "surface" area per circular mil, and therefore, has more ampacity.

Post more later,
Doc

Does it run on the surface? That is what I was taught 20 years ago in trade school. Now I hear that it does not, it runs through the center of a conductor.

The higher the frequency the more the current flows near or on the surface of the conductor(see previous posts for skin effect).Since 60 Hz is fairly low in frequency IMO I believe it would flow near the center of the conductor.
Chris

NJwirenut,
Not true according to UL. See guide RTRT.

Don

[This message has been edited by resqcapt19 (edited 12-12-2002).]

Alternating current flows closer to the outside of the conductor which is called the "skimming effect" or "skin effect".

[This message has been edited by ayrton (edited 12-12-2002).]

I can dig it Chris. That's why at high freq's skin effect is so critical. Effectively the "cross sectional area" of the conductor is reduced when the current runs along the outside of the conductor. I, like Wnuttt, was taught that current runs on the surface. And, just recently, I was reading about the effects high freq's in a conductor.
At what freq range does skin effect become critical? I don't know? But, from the confidence that was vibrating from your reply, I'll take your word for it. I love the dynamics of this forum. As iron sharpens iron, one ECN member sharpens another.
To get back to the original post....I think that emf, counter emf, etc., etc. etc. are more a product of the load that is served rather than the conductor serving the load.
The acception would be voltage drop, which is a product of the wire (area in CM), and the current (load), along with the rest of the factors in the voltage drop formula.

Dull as spoon,
Doc

Stranded vs. Solid -- In practical application there's little difference in electrical performance between stranded and solid wire. The DC resistance of stranded wire is slightly more than solid wire of the same gauge, due to the slightly smaller total conductor cross-sectional area. But stranded wire has slightly less impedence at high frequencies, due to the slightly larger surface area. So, stranded wire is generally preferred for most applications because of it's much greater flexibility, but solid might be preferable for high power (and especially high current) applications.

UL will say it's suitable. However I guess the issue of what type of wire vs. type of connector also hinges on what is easier to work with a particular type of terminal.

For instance, when it comes to screw terminals (like those found on wall switches and receptacles), solid is easier to work with once you've got the hook done. You don't have to worry about individual conductor strands coming out from under the screw as it tightens, like it happens when attching a cord cap or a lampholder to a piece of lamp-cord.

When twisting two conductors and attaching a wirenut, stranded is easier because you can twist it partly with your fingers - you don't need a linesman's pliers.

There is a lot of myth about where current flows.

I suspect that A/C current that flows at the surfaces of stranded conductor refers to current that flows near the insulation of the conductors rather than at the surfaces that are interior to the whole wire.

I suspect that there is no real current carrying difference between identical x-section stranded and unstranded wire.

The only difference is: Stranded is easier to bend.

Skin effect is neglible to non existent at and below 60Hz, until you get into the 250kcmil and larger wire sizes.

Skin effect is a function of the frequency, and the overall diameter of the conductor. As far as skin effects goes, it makes no difference if the conductor is solid or made up of strands.

When is skin affect needed? How about antenas, I see that they are hollow and work at a very high frequency.