I have been trying to understand wire gauge for a project, but there are so many different strand types and sizes it's alittle overwhelming. The wire needs to be 30 AWG and stranded, is it common for 30 AWG to have 7 strands or can it have more like 26?
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\$\begingroup\$ It can have as many strands as the manufacturer is willing to do \$\endgroup\$– PlasmaHHCommented Jul 20, 2018 at 10:46
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\$\begingroup\$ Ok understood, would there be much difference in a 7 strand cable Vs 26 strand? Flexibility / data transfer wise. \$\endgroup\$– Lanegreens38Commented Jul 20, 2018 at 10:56
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\$\begingroup\$ Flexibility yes, but the isolation is probably the limit here anyway. Data transfer is highly unlikely. \$\endgroup\$– winnyCommented Jul 20, 2018 at 11:06
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\$\begingroup\$ So would a higher strand count have increased flexibility or the lower count? Sorry for all the questions, but why would the isolation be the limit, due to the diameter? \$\endgroup\$– Lanegreens38Commented Jul 20, 2018 at 11:10
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\$\begingroup\$ Resistance is only determined by area (mm^2). Flexibility and fatigue life are improved by more, finer strands. Cost, corrosion resistance are improved by fewer. House wiring (not flexible) is 2,3 or 5 strands each 0.5mm^2. Hookup wire (flexible, but fixed in use) is 7 strands. This soft Multimeter wire has up to 1050 strands aliexpress.com/store/product/… \$\endgroup\$– Henry CrunCommented Jul 20, 2018 at 11:47
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1 Answer
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The stranding is more-or-less arbitrary, determined by the sizes of individual conductor that the manufacturer can make and how they are combined. The differences are (almost) entirely physical, electrically there is very little difference between a wire with many strands (all touching each other) and one with a single core.
Mechanical characteristics include:
- flexibility
- lifetime when bent
- break strength
- corrosion resistance (as mentioned by @Henry Crun)
The first two generally increase with the number of strands (but the insulation also can have a large effect).
Diameter variations with stranding will affect the electrical characteristics (eg. inductance, capacitance) only slightly, and rounding from the nominal gauges of strands leads to some slight difference in nominal resistivity though the target is the same resistance per unit length (because the total cross sectional area of the conductors should be the same regardless of stranding).
Eg. an AWG30 wire has a nominal cross-sectional area of 0.0509mm^2. If there are more than one strand then they should add up to that area.
For example, here is an excerpt from the standard stranding chart of a specialty wire manufacturer:
They offer as many as 40 strands of AWG46 wire (as standard). The nominal OD increases for coarse stranding in particular, but in this case only by about 20% for the coarsest stranding.
This particular maker can make single core wire as fine as AWG 56 so you might imagine that (for enough money, and it would be a large amount) they could make an AWG 30 conductor with ~420 strands of AWG 56 wire.
Note that this only covers the conductor. The insulation system is another subject entirely and pretty much independent of the conductor.
answered Jul 20, 2018 at 12:44
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\$\begingroup\$ Thank you very much for that detailed response! So for my situation I need a flexible 30 AWG cable, so with the Information you provided the higher the strand count will mean increased flexibility, the cable I was looking at is AWG 30 with 26 strands 0.005 cross section, so it should be quite flexible. Unfortunately the seller doesn't have all the colours I need, where would be the best place to source this, such as the high strand count maker you mentioned? \$\endgroup\$ Commented Jul 20, 2018 at 13:23
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\$\begingroup\$ For hobby purposes you're just going to have to shop around. I don't have any magic supplier list. Ten colours is a pretty good selection. Beyond that it often gets to stripes or spots, difficult on a #30 wire. \$\endgroup\$ Commented Jul 20, 2018 at 13:39
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\$\begingroup\$ You may want to look into purchasing ribbon cable and stripping it \$\endgroup\$ Commented Jul 20, 2018 at 14:35
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\$\begingroup\$ Though usually ribbon cable repeats after 10 colours. \$\endgroup\$ Commented Jul 20, 2018 at 14:56
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\$\begingroup\$ The colours that are needed are Green, Black, Red and White which are common, what isn't so common is a strand count above 7 for a 30 AWG cable sadly. Although as @davidmneedham stated there is probably not much a difference. \$\endgroup\$ Commented Jul 20, 2018 at 15:03