Ok, my inspections are a little slow between the holidays and so have time to market and produce little educational displays for my clients. I had read somewhere before that securing different wires sizes to a board… with wires most likely to be found in residential systems was a good idea, so I did just that.
Now my discovery:
I purchased 1 foot chunks of all the main wire sizes from my local Home Depot, and miked them out with my micrometer (accurate down to .001). I discovered that 100% of wires are actually 1 gauge larger than is printed on the side. For example wiring sold as 3/0 is actually 4/0 as gauged by the micrometer, and for a second example 8 AWG actually miked to 7 AWG @ 0.14 inches per the charts… and so on and so fourth. Has anyone else discovered this or know this?
My question now is why? Is this because the wire manufactures are providing a margin of safety in their advertised wire sizes to account for bends and kinks and such? I understand there is not suppose to be an appreciable difference in current flow between stranded and solid wire (except over very long runs not normally found in residential electrical systems). The solid core GEC / ground wiring miked exactly true to gauge…
Anybody have ideas?