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Wire Table

Units are a mess when it comes to coiling - long after UK has gone metric the former colonies still stick to imperial units! To make it worse there are two wire gauges standards British swg and American which are not quite equal. Inductance formula's require measurements in inches, the calculator programs work out wire lengths in feet. We buy wire by the half kilo, they buy it in lbs. I have suggested that we move everything metric but will they listen.....

Meanwhile this table might help, or it might not!

 

USA

awg

UK 

swg

metric

dia mm

meters

per 0.5kg

feet

per 0.5kg

turns

per inch

Amps resistance

ohms/1000ft

32.00 36.00 0.20 1850 6086 125 0.05 167.30
30.00 33.00 0.25 1120 3684 100 0.08 105.20
28.00 30.00 0.32 705 2321 79 0.12 66.17
26.00 27.00 0.40 438 1439 63 0.19 41.16
24.00 25.00 0.50 280 921 50 0.30 26.17
23.00 24.00 0.56 223 734 45 0.38 20.76
22.00 23.00 0.64 170 558 39 0.50 16.46
21.00 22.00 0.71 139 457 35 0.61 13.05
20.00 21.00 0.80 109 360 31 0.78 10.35
18.00 19.00 1.00 70 230 25 1.21 6.51
 16.00 18.00 1.25 45 147 20 1.89 4.09
 15.00 17.00 1.50 31 102 17 2.72 3.25
 14.00 16.00 1.60 27 90 16 3.10 2.58
12.00 14.00 2.00 18 58 13 4.84  1.61

 

DC Wire Resistance against diameter in mm

ChartObject Chart 1

While this is interesting it is not the whole story first of all the AC resistance is higher than the DC resistance because of the skin effect - (see the transformer page). Plus resistance is only one of the sources of loss - there is also the effects of inter turn capacitance, eddy losses and ionisation losses all of which take energy out of the system and add to the effective impedence - lowering the Q.

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