That night, Leo re-wired the jukebox with 10 AWG. The tubes glowed warm, the records spun, and when the first notes of “Johnny B. Goode” boomed out, the wire stayed cool.

Once the gauge drops below 1, the size is denoted by zeros (pronounced "aught").

Leo looked back at the jukebox. The burned wire had been a near miss.

His grandfather handed him a worn, greasy card. “Three rules,” he said. “One: length matters. A long 10 AWG wire acts like a short 14 AWG wire, so go thicker for long runs. Two: amperage is king. Find the device’s draw, look at the chart, and always pick the next size up. And three…” He tapped the 10 AWG cable. “When in doubt, go down a number. Heavier is safer.”

As the gauge number increases by 6 (e.g., from 10 to 16), the wire diameter is roughly halved.