By providing resistance per foot, the chart allows professionals to calculate voltage drop over long runs (e.g., 100+ ft from a solar panel to a charge controller). This is something cheap online calculators often get wrong.
4/5 – Indispensable for pros, dangerous for amateurs without a disclaimer. awg wire size chart
Good charts include ampacity for 60°C, 75°C, and 90°C insulation. This is vital for matching wire to breaker terminals (most breakers are rated 60/75°C). The Cons – Where It Confuses Users 1. The Inverted Logic New users constantly ask: “Why does a smaller number mean bigger wire?” The historical reason (drawing dies) doesn’t help. The chart does nothing to explain this cognitive hurdle. By providing resistance per foot, the chart allows
The chart’s most valuable column is ampacity (current-carrying capacity). It prevents fires: a 14 AWG wire is rated for 15A, 12 AWG for 20A, 10 AWG for 30A, etc. Ignoring this is the #1 cause of residential electrical fires. Good charts include ampacity for 60°C, 75°C, and
you understand NEC derating. Avoid it if you just want to know “what wire for a 20A breaker?” – in that case, memorize: 14 AWG = 15A, 12 AWG = 20A, 10 AWG = 30A and ignore the chart’s complexity.
The chart is based on solid wire. Stranded wire (more flexible) has a slightly larger overall diameter for the same gauge. Most printed charts omit this, leading to DIYers buying stranded wire that won’t fit into a push-in connector.