David Wrigley's Web Page:Microwave Sources David Wrigley's Microwave Website Tinned Copper Wire and Fuse-wire These tables are calculated and not the result of experiment. They are published as a guide only and not as an authoritative document. The fusing currents have been calculated from basic physical properties (tinned copper) and may vary in practice with different positions, air circulation etc The fuse ratings are assumed to be half fusing current. The wire ratings are based on cable ratings of 8500A/sq in and in practice this max rating will depend on ambient temp, insulation, position and cable life expectancy. Cables can be run at higher currents and temperatures only if the insulation can stand it! This information is for experimental use only by careful and competent persons and in no circumstances should it be used for any other purpose. No legal liability will be accepted for any consequences following from the use of this information. Installations in buildings within the UK must follow the appropriate British Standard AWG SWG Diameter CSA Fusing Current Fuse Rating Wire Rating mm sq mm Amps Amps Amps 32 0.202 0.032 7 4 0.4 35 0.214 0.036 8 4 0.5 31 34 0.226 0.04 9 5 0.5 33 0.250 0.049 10 5 0.6 30 0.255 0.051 10 6 0.7 32 0.269 0.057 11 6 0.8 29 31 0.288 0.065 12 7 0.9 30 0.315 0.078 14 7 1.0 28 0.321 0.081 15 8 1.1 29 0.331 0.086 15 9 1.1 27 0.362 0.103 17 10 1.4 28 0.397 0.124 20 10 1.6 26 0.404 0.128 21 10 1.7 27 0.410 0.132 21 12 1.7 25 26 0.454 0.162 24 14 2.1 25 0.496 0.193 28 15 2.5 24 0.517 0.21 30 17 2.8 24 0.559 0.245 33 17 3.2 23 0.574 0.259 35 19 3.4 23 0.613 0.295 38 21 3.9 22 0.642 0.324 41 25 4.3 22 0.723 0.41 49 25 5.4 21 0.724 0.412 49 29 5.4 21 0.807 0.511 58 31 6.7 20 0.841 0.556 62 34 7.3 This is a table for thinner wires. These can be useful as solder-in 'last ditch' fuses on experimental PCB's. For example, a thin soldered-in fuse in front of a shunt diode can protect a pcb from reverse polarity damaging components, whilst at the same time causing minimal energy loss. Initially, this could be a thin track on the PCB which, can be replaced by a wire if it blows. - a useful source of thin wire for these low current fuses can be found in the braid of screened cables - NB the fuse rating is the operational current that the fuse normally carries Fuse Cable Rating dia (mm) Dia (in) area mm2 fusing current A/sq mm SWG Rating A @8500A/sq in A A A @13.2A/mm2 0.05 0.00 0.00 1.00 441.00 47.00 0.50 0.03 0.09 0.00 0.01 2.00 347.00 43.00 1.00 0.08 0.11 0.00 0.01 3.00 305.00 41.00 1.50 0.13 0.13 0.01 0.01 4.00 278.00 39.00 2.00 0.19 0.16 0.01 0.02 5.00 257.00 38.00 2.50 0.26 0.25 0.01 0.05 10.00 204.00 33.00 5.00 0.64 0.33 0.01 0.08 15.00 178.00 30.00 7.50 1.11 0.40 0.02 0.12 20.00 162.00 28.00 10.00 1.63 (C) David Wrigley 2000-3 Last updated October 2003 http://www.microwave.fsnet.co.uk/info/wire.htm (1 of 2) [5/10/2005 12:16:13 PM] David Wrigley's Web Page:Microwave Sources 19 0.900 0.636 68 35 8.4 20 0.917 0.66 70 41 8.7 19 1.017 0.813 82 42 10 18 1.026 0.826 83 49 11 17 1.151 1.04 99 54 14 18 1.221 1.17 108 60 15 16 1.306 1.34 119 69 18 17 1.441 1.63 138 71 21 15 1.463 1.68 141 83 22 14 16 1.627 2.08 166 99 28 13 1.830 2.63 198 99 35 15 1.833 2.64 199 116 35 14 2.034 3.25 232 139 43 11 2.293 4.13 278 147 54 13 2.386 4.47 295 167 59 10 2.588 5.26 333 170 69 12 2.620 5.39 339 197 71 9 11 2.899 6.6 395 237 87 8 3.270 8.4 473 270 110 10 3.568 10 539 282 130 http://www.microwave.fsnet.co.uk/info/wire.htm (2 of 2) [5/10/2005 12:16:13 PM]