ECN Forum Forums Code Related Discussion NEC & other Code issues all strands under one lug or terminal

The ampacity of wire at 60Hz is driven more by the temperature rise the insulation sees. Not skin effect. If you have stranded wire with 7 strands (one in the center, 6 outside) the strand in the middle has no easy way to shed the extra heat, as it's surrounded by the other strands that are also getting hot. So you can't just add up the ampacities of the individual strands ("Looks like 12 guage wire, so that's 20 amps times 7"). It's less than that. But you will see less voltage drop at the rated ampacity then what you'd see if it were valid to add the ampacity of the individual strands.