Modern wire sizing.

Cross-sectional area, I would guess. No doubt someone can confirm or correct that as the case may be.

That's the diameter.

Correct. Calculating the area via pi.r^2:

r=0.19/2 pi*(0.19/2)^2 = 0.02835

which is near enough.

No, they use all kinds of sizes.

Usually stranded wires are written as 7/0.1 which means 7 strands of 0.1mm diameter wire. You can get many different combinations of diameter and number of strands. Then of course you get multicore cable which might have

Electrical power cable is instead measured by the mm2 cross-sectional area, being either class 1 (solid core), class 2 stranded (eg 7 strands in normal domestic sizes), or class 5 or 6 flexible (many more strands):

- so for example Twin and Earth cable is 2x2.5+1.5 which means two cores of 2.5mm2 plus an earth core of 1.5mm2 (all solid)

Then you have all the different types of cable which usually relates to the insulation and the makeup of the cable rather than the conductors.

And Then you have Americans, who measure it all in AWGs ('gauge') instead. (and their 14/2 means two conductors of 14 awg each)

Theo

This is speaker wire, for low voltage usage, so just don't ever use it for mains voltage. It is multi-stranded primarily for flexibility (likely to vibrate under the influence of the speaker), and HiFi 'purists' might say there is a electronic reason for using multi-stranding instead of solid core (or maybe the opposite, I wouldn't know).

Technically it was known as doorbell wire.

Definitely OK up to midfi levels for audio. Bigger stranded silicone cable is made for serious power levels and best bass damping or for any high current wiring needing low resistance and good mechanical flexibility

I have used it for light pendants and (slaps wrist) mains table lamps as well

There was a version rated for mains voltage - twin "shotgun" cores but with thicker insulation than the audio version - that was quite common at one time for things like lamps. Not allowed now as the regs require two layers of insulation.

Mike

42/0.2 is a common speaker wire size. That gives 1.32 mm^2.

There is a variation in what the cable wires may be made from. Copper or Copper plated Steel or Aluminium

Also the fake cables where the numbers may be a work of fiction.

The Skin Effect applies at any frequency, to one extent or another. Using a multitude of tiny strands, is an attempt to conduct the AC frequencies better (for a given total cross-section of cable).

From a Google:

"at 50 Hz or 60 Hz the skin depth in copper is around 9 mm (Fig. 1a, b). This is partly the reason for the high-current busbars in low-voltage switchgear to be made with copper bars not thicker than 10 mm "

Paul

However, for stranded wire at audio frequencies its pretty much something you canb ignore...

Multiple strands in speaker wire are for flexibility. If skin effect is an issue you'd use eg Litz wire where each tiny strand is insulated. A bugger to solder though. A molten NaOH bath is a good way to strip it.

Multiple strands in speaker wire are for flexibility. If skin effect is an issue you'd use eg Litz wire where each tiny strand is insulated. A bugger to solder though. A molten NaOH bath is a good way to strip it.

Not necessarily. There is no doubt that stranded non Litz wire is better than solid core for longish runs of e.g. audio and indeed HV grid cables.

How *much* better is the issue.

In general for signal applications the whole cable impedance is very low relative to the end point impedances.

Which is why e.g. CAT 5 house wiring is solid core.

About the only domestic application - and its marginal - where stranded makes a difference in signal levels is audio speaker cables.

Haven't seen it in years. They uses to use it for the long wave part of ferrite road aerials in portable radios. And in some valve sets

In general a transistor to add gain is a lot cheaper than a litz wire coil. :-)

But if there isn't enough signal to start with just amplifying what you have isn't going to help. An extra few dB of 'real' signal might make all the difference.

Cheers!

Oh yeah, I am not daft enough to use it for mains leccy!

I was just curious abou the nomenclature and measurements, etc.

As for Hi-Fi folk, it has been revealed to me in a series of copper scroll found buried in the woods that most of the "purists" have quite obviously not bothered to take even the most rudimentary measures of their own hearing using a tone generator and headphones (or their stereo), and had a go at using low- and high-pass filters on digital copies of their music, both tasks can be done with the free software "Audacity". The copper scrolls have stated that these people probably listen to the difference of reproduction of their venerated Hi-Fi equipment of choice rather than the music itself. Each to their own of course.

What power levels are you talking about when you say "serious"?

Is the silicon insulation important, or is that just a desirable thing for flexibility or something? Surely the copper will be the overarching flexibility factor?

Even I wouldn't do that, and I know nowt.

Cheers.