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I do not think the "skin effect" is significant @ 60 Hz.

There has been some good discussion in this thread on extension cords, both pro and con. Like the two versions of electrical requirements, which Jim reports being related to Emerson, there are also at least two versions of extension cord requirements in the manual. These are in the form of various minimum AWG for each maximum cord length. I'm looking at an early 80's manual Vs a late 80's manual, and lean toward thinking that this change in specs also correlates with the introduction of the Emerson motor. For example, the old manual specifies a minimum wire size of 16 AWG for a cord length up to 25 feet and the later manual makes this 14 AWG. Similarly for 50 feet 14 AWG changed to 12. For 100 feet they both say 10 AWG. Stranded wire is pretty standard for extension cords.

Given Jim's / Emerson's reasoning for the OCP change in power requirements, I think it is reasonable to assume that this change is meant to reduce preventable warranty failures of motors.

Personally, I don't use extension cords smaller than 12 AWG in my shop for anything regardless of length. I use them without hesitation when it is convenient to do so.

- David

JPG wrote: Tue Mar 18, 2025 10:32 pm I do not think the "skin effect" is significant @ 60 Hz.

Correct. Assuming Cu wire, the skin effect @60Hz would be about 4 times the diameter of standard solid 12AWG. In other words, at 60 Hz, the current density would be nearly uniformly distributed through solid 12AWG Cu wire, i.e. don't worry about skin effect at 60Hz.

https://www.arrow.com/en/research-and-e ... kin-effect