The fusing current in amperes at which a wireWILL MELTcan be calculated from the constant (K) that depends on the metal used multiplied by the square root of the wire diameter in inches.
Owing to a wide variety of factors that can influence the rate of heat loss, these figures must be considered as only approximations.
If the power supply will provide more current (without shutting down or tripping a circuit breaker or fuse) than the fusing current listed it is not a good idea to use that size wire.
| Melting temperature | |||||
| Type of Metal | Copper | Aluminum | German Silver | Iron | Tin |
| Constant (K) | 10,244 | 7585 | 5230 | 3148 | 1642 |
| degrees in C/F | 1083/ 1981.4 |
660/ 1220 |
961/ 1761.8 |
1533/ 2791.4 |
232/ 449.6 |
| FUSING CURRENTS IN AMPERES | ||||||
| AWG B∓S Gauge |
Diameter in inches | Copper | Aluminum | German Silver | Iron | Tin |
| 40 | 0.0031 | 1.77 | 1.31 | 0.90 | 0.54 | 0.28 |
| 38 | 0.0039 | 2.50 | 1.85 | 1.27 | 0.77 | 0.40 |
| 36 | 0.0050 | 3.62 | 2.68 | 1.85 | 1.11 | 0.58 |
| 34 | 0.0063 | 5.12 | 3.79 | 2.61 | 1.57 | 0.82 |
| 32 | 0.0079 | 7.19 | 5.32 | 3.67 | 2.21 | 1.15 |
| 30 | 0.0100 | 10.20 | 7.58 | 5.23 | 3.15 | 1.64 |
| 28 | 0.0126 | 14.40 | 10.70 | 7.39 | 4.45 | 2.32 |
| 26 | 0.0159 | 20.50 | 15.20 | 10.50 | 6.31 | 3.29 |
| 24 | 0.0201 | 29.20 | 21.60 | 14.90 | 8.97 | 4.68 |
| 22 | 0.0253 | 41.20 | 30.50 | 21.00 | 12.70 | 6.61 |
| 20 | 0.0319 | 58.40 | 43.20 | 29.80 | 17.90 | 9.36 |
| 19 | 0.0359 | 69.70 | 51.60 | 35.50 | 21.40 | 11.20 |
| 18 | 0.0403 | 82.90 | 61.40 | 42.30 | 25.50 | 13.30 |
| 17 | 0.0452 | 98.40 | 72.90 | 50.20 | 30.20 | 15.80 |
| 16 | 0.0508 | 100.00 | 86.80 | 59.90 | 36.00 | 18.80 |
| 15 | 0.0571 | 140.00 | 103.00 | 71.40 | 43.00 | 22.40 |
| 14 | 0.0641 | 166.00 | 123.00 | 84.90 | 51.10 | 26.60 |
| 13 | 0.0719 | 197.00 | 146.00 | 101.00 | 60.70 | 31.70 |
| 12 | 0.0808 | 235.00 | 174.00 | 120.00 | 72.30 | 37.70 |
| 11 | 0.0907 | 280.00 | 207.00 | 143.00 | 86.00 | 44.90 |
| 10 | 0.1019 | 333.00 | 247.00 | 170.00 | 102.00 | 53.40 |
| 9 | 0.1144 | 396.00 | 293.00 | 202.00 | 122.00 | 63.50 |
| 8 | 0.1285 | 472.00 | 349.00 | 241.00 | 145.00 | 75.60 |
| 7 | 0.1443 | 561.00 | 416.00 | 287.00 | 173.00 | 90.00 |
| 6 | 0.1620 | 668.00 | 495.00 | 341.00 | 205.00 | 107.00 |