Hi Nicholas, I made a TC primary with indoor romex 14-2 wire. Here's
how: I stripped off all the insulation, outer jacket and the white
and black leaving three bare number 14 wires. Secure one end each of
the three wires with a vise or clamp to a solid work table. Keep the
three wires straight and close together and using a drill gun
(plug-in or cordless), insert the free end of the three wires in the
chuck that would normally secure the drill bit. With the three bare
wires straight and suspended between the anchor vise and the drill
gun, slowly turn on the drill gun and the three bare wires will
eventually tightly wrap together forming a wider solid conductor. The
diameter of the wire bundle is about 0.2 inches. The wire will set
together and will not unwrap. You will lose some overall length as
the wire wraps together so if you need 40' then I'd get a 50' box of
wire (about $29. locally). It's not rocket science, the finished
product looks nice and you can say that you made it yourself.
Caution, use eye protection and watch out for kinks and mechanical
forces stored in twisting wire (keep kids and pets out of the way)
when wrapping the wire. Keep the wire stored in a loose loop until
used. Good Luck, Bob Wroblewski Dracut, MA