Hey - what you guys doing highjacking the thread?
Well - my question was answered at least, I was only worried about the ease of installation and working with the cable for my application, I wasn't at all concerned about signal strength. But I may as well dive in!
It's funny, I was just talking to guys at work about the solid vs. stranded for carrying a stronger signal that was mentioned on here, and got a few comments from them. Mostly in one respect - the cable will perform as well as it's rated. It wouldn't be rated Cat6, stranded or solid, if it couldn't do its job. So there shouldn't be a fear that bits will be lost because of choosing one of the other. Just choose the one that's easiest to work with for your application. Cat6 is rated for certain rates up to certain max distances. The solid will do it, the stranded will do it. Go beyond those distances and you are operating out of spec, and you can't trust the solid or the stranded. Within spec you can trust either (assuming it comes from a trusted manufacturer that certifies their cables). In addition, very complex effects with electrons start to take place at high frequencies, that most of us don't understand well, having to do with electric and magnetic field interactions.
As for theory. As far as I understand, for low frequencies the cross sectional area is of most importance. At 60 Hz and DC, power supply frequencies, cross sectional area is king. As frequencies climb however there is something called the "skin effect" which makes itself manifest and current tends to run on the outside of the conductor. There is also something called "proximity effect" but I don't understand the details, has something to do with current eddies and weird stuff like that. Skin "depth" is several millimeters (like 8 or something like that) at 60 Hz, so only has an effect on very large power cables.
Skin effect is more pronounced at high frequencies. At 100 MHz, the skin depth (where the current density drops to 1/e) is about 6.5 micrometers. For Cat6, which is rated up to 500MHz, skin effect could be very significant. In these cases, the surface area of the outside of an uninsulated cable bundle is likely what's important. In fact, for RF applications, hollow tubes are often just as effective. Stranded vs. solid should have a negligible effect as long as the outer diameter is the same. Since they are shorted together the bundle acts
mostly as a single conductor. I would guess 24 ga stranded will be about the same diameter as 23 ga solid. The capacitance values for each type of cable are very similar as well, my guess is because the electrical properties of shorted strands vs. a solid conductor are similar.
So as a EE myself, I just don't buy it that solid conductor of comparable diameter as stranded could carry a signal significantly better over longer distances based on the theory I have learned. I also don't buy it because if it meets the spec it meets the spec. Maybe the solid can go a few feet further or not. I would think manufacturing variances would make just as big of a difference. So my guess is that solid is better for long, permanent runs because it can handle oxidation better over time, is more durable so pulling is less likely to damage it, and pulling stress goes up with pulling cable over longer distances, and not because of a difference in electrical properties. The idea that solid is electrically superior, in my opinion, would be conjecture and has become "truth" just because of speculation over the fact that solid is recommended by manufacturers as more reliable for pulling and in wall use. A quick search on the internet, and I found many manufacturers recommending solid for long distance use and in wall use - but none of them ever said why. I would be very interested in a study or paper discussing the reasons
why solid is recommended for long distances.
