Eroica - Q. What is “enamelled-copper”?

Eroica - Q. What is “enamelled-copper”?

Answer:

The windings of each coil must be insulated from each other and this is achieved these days by a thin layer (2 microns) of polyester.  In the past, coil windings were dipped in an enamel varnish which was much heavier and thicker and is no longer used; but the old name “enamelled” has stuck and is still used, even when we mean polyester!