Glossary of Terms Appendix B: Wire Gauge & Material Tables Complete reference tables for wire properties used in VIC choke design. All values at 20°C (68°F) unless noted. AWG Wire Gauge Reference AWG Diameter (mm) Diameter (in) Area (mm²) Area (kcmil) Cu Ω/1000ft Cu Ω/km 10 2.588 0.1019 5.261 10.38 0.9989 3.277 12 2.053 0.0808 3.309 6.530 1.588 5.211 14 1.628 0.0641 2.081 4.107 2.525 8.286 16 1.291 0.0508 1.309 2.583 4.016 13.17 18 1.024 0.0403 0.823 1.624 6.385 20.95 20 0.812 0.0320 0.518 1.022 10.15 33.31 22 0.644 0.0253 0.326 0.642 16.14 52.96 24 0.511 0.0201 0.205 0.404 25.67 84.22 26 0.405 0.0159 0.129 0.254 40.81 133.9 28 0.321 0.0126 0.081 0.160 64.90 212.9 30 0.255 0.0100 0.051 0.101 103.2 338.6 32 0.202 0.0080 0.032 0.063 164.1 538.3 34 0.160 0.0063 0.020 0.040 260.9 856.0 36 0.127 0.0050 0.013 0.025 414.8 1361 38 0.101 0.0040 0.008 0.016 659.6 2164 40 0.080 0.0031 0.005 0.010 1049 3441 Highlighted rows indicate commonly used gauges for VIC chokes. Wire Material Resistivity Material Resistivity ρ (Ω·m) Relative to Cu Temp Coefficient α (/°C) Silver (Ag) 1.59 × 10⁻⁸ 0.95× 0.0038 Copper (Cu) 1.68 × 10⁻⁸ 1.00× (reference) 0.00393 Gold (Au) 2.44 × 10⁻⁸ 1.45× 0.0034 Aluminum (Al) 2.65 × 10⁻⁸ 1.58× 0.00429 Brass 6-9 × 10⁻⁸ 4-5× 0.002 Steel 1.0 × 10⁻⁷ 6× 0.005 Stainless Steel 6.9 × 10⁻⁷ 41× 0.001 Nichrome 1.1 × 10⁻⁶ 65× 0.0004 Temperature Correction Resistance at Temperature T: R(T) = R₂₀ × [1 + α(T - 20)] Example (Copper wire): R₂₀ = 10 Ω at 20°C At 50°C: R = 10 × [1 + 0.00393(50-20)] = 10 × 1.118 = 11.18 Ω At 80°C: R = 10 × [1 + 0.00393(80-20)] = 10 × 1.236 = 12.36 Ω Magnet Wire Specifications Magnet wire has enamel insulation. Overall diameter includes insulation: AWG Bare Dia. (mm) Overall Dia. (mm) Turns/cm Turns/inch 18 1.024 1.09 9.2 23.3 20 0.812 0.87 11.5 29.2 22 0.644 0.70 14.3 36.3 24 0.511 0.56 17.9 45.4 26 0.405 0.45 22.2 56.4 28 0.321 0.36 27.8 70.6 30 0.255 0.29 34.5 87.6 32 0.202 0.24 41.7 106 Current Capacity Guidelines For chassis wiring (in open air): AWG Max Current (A) AWG Max Current (A) 10 15 24 1.4 12 9.3 26 0.9 14 5.9 28 0.55 16 3.7 30 0.35 18 2.3 32 0.22 20 1.8 34 0.14 22 2.1 36 0.09 For coils, derate by 50% due to limited cooling. Magnet wire rated for higher temperature can handle more current. Skin Depth Reference At high frequencies, current flows near the wire surface. Skin depth δ: δ = √(ρ / πfμ₀μᵣ) Skin Depth in Copper: Frequency Skin Depth (mm) Max Useful Wire Dia. 1 kHz 2.1 mm ~4 mm (AWG 6) 10 kHz 0.66 mm ~1.3 mm (AWG 16) 50 kHz 0.30 mm ~0.6 mm (AWG 22) 100 kHz 0.21 mm ~0.4 mm (AWG 26) Use wire diameter ≤ 2×δ for effective use of conductor cross-section. For larger currents at high frequencies, use Litz wire. Quick Reference: DCR Calculation For Copper Wire: DCR (Ω) = Length (m) × Resistance (Ω/km) / 1000 DCR (Ω) = Length (ft) × Resistance (Ω/1000ft) / 1000 For Other Materials: DCR material = DCR Cu × (ρ material /ρ Cu )