A question about wire... - Page 1
Forum section: electronics / beginners

author: _jryan
author_rank: Newbie
timestamp: October 05, 2019, 03:47:38 pm
content: Hello everyone,I am shopping around for wire - 22 awg, stranded - and would really like to to try out the silicone rubber insulated. All the stranded wire is tinned which I'm normally fine with but am hesitant in this case. I was hoping someone here could fill in some of my information gaps.Some of the Amazon commentors mentioned how fine the strands are so I looked for a strand count in the product spec. No dice. I checked numerous similar products - possibly the same manufacturer - and most didn't specify though I did find one which stated 60 strands in a 22 awg wire.That's a lot finer than I like but could live with it if the strands were not tinned. And this is my problem...The tin cladding is very thin but in this case so are the strands. With 60 strands in a 22 awg wire wouldn't that tin cladding add up to a substantial percentage of the overall wire mass? Tin is not a great conductor, compared to copper, and wouldn't this affect the overall performance of the wire? It's also a lot cheaper than copper and this is a pretty tricky way to lower the cost of a wire, imho.I have no idea what the tin cladding thickness would be so I don't know what the tin / copper ratio could be. And, it could even be that it doesn't matter at all. But I don't know and was hoping someone here could give me some insight.Thanks!jay

author: _jryan
author_rank: Newbie
timestamp: October 05, 2019, 04:24:15 pm
content: A short addendum...Generally, these wires would be used for low current hookups but I can see, on occasion wanting to run upwards of 2 amps through the wires. In testing, for a finished project I would probably get different wire if I had to.That said, these are the current ratings for 22 awg found onhttps://www.engineeringtoolbox.com/wire-gauges-d_419.html:1 core -> 5.0 amps<4 cores -> 3.0 amps4-6 cores -> 2.4 amps7-24 cores -> 2.1 amps25-42 cores -> 1.8 amps>42 cores -> 1.5 ampsOf course, current rating drops as number of strands gets higher and I wonder if it would drop more as tin content rises. Could the amount of tin also affect the frequency rating?

author: james_s
author_rank: Super Contributor
timestamp: October 06, 2019, 01:02:59 am
content: Silicone insulation is typically used when you want high current resulting in high temperatures and maximum flexibility without fatigue hence the high strand count. I use it in my RC airplanes and quadcopters for the battery and motor wiring.Is there a particular reason you want to use silicone wire? Because it doesn't sound like you need the characteristics it offers.

author: ArthurDent
author_rank: Super Contributor
timestamp: October 06, 2019, 02:48:23 am
content: You have misinterpreted what the table you referenced means.First, attached below are the specs on common #22AWG stranded hook-up wire from Belden. It is PVC insulated, 7 strands of #30 tinned copper wire. You want the wire tinned if you plan on soldering it as bare copper wire corrodes rapidly and is therefore harder to solder. This is the standard #22 stranded hook-up wire you would probably get no matter where you buy it or who made it. The #30 individual tinned strands have an area of .049 mil square and 7 strands of #30 would have about .343 mil square. Your table shows that #22 wire has .330 mil square so this makes sense. If the wire was made for test leads like those for a DMM then it probably would have many more strands and silicone insulation to make it more flexible. Some of the higher current test leads I have contain 254 strands of very fine wire.When you mention the current carrying capacity of the various 'cores' that means that if you make a cable with an outer jacket that has a certain number of wires, or cores, in order to keep the heat radiated by wires in the cable down, you have to derate the current handling capacity of the wires in the cable. It has nothing to do with whether the individual insulated wires are stranded or solid. If you were making a cable, or bundle, of 42 or more wires, the individual #22 insulated wires would be derated from 5 amps to 1.5 amp current capacity as your list shows.