JIMMIE wrote in
:

Just wondering how a few mils of PVC insulation would effect the
permittivity of a couple of 12 guage wires spaced a couple of inches
apart.

By "mils", do you mean thousands of an inch? (The rest of your dimensions
are imperial.)

I doubt it would make much difference

The easiest way I know of to assess the effect of the mixed dielectric
environment, is to measure the velocity factor, and use that to infer an
equivalent permittivity (as I noted in my earlier post).

Owen