Insulation done! Shop heater questions. Electrical gurus.

!!NO!! Sorry, not true. If this WERE true, then it means your wiring is seriously undersized, and that you are headed for a house fire.

Wattage for electric heat (resistive) is a simple calculation of amps x voltage. If there were any significant loss due to wiring (otherwise know as " I squared R") then your wiring is in BIG trouble.
Hmmm. I don't necessarily disagree with your statement although I think you might have taken it farther than I was representing.

I did point out the calculation for Watts "Watts are calculate by multiplying amps and volts," I also pointed out the relationship between Amp and Ohms " keep in mind that amp values are influenced by resistance ,or Ohms."

The point I was making is that heat does impact and change the resistance value. I did not put a number on the value because it could be negligible to severe. That even a subtle change in resistance could have an impact on the bill. Will it be noticeable?? eh. it's a technical position in principal.

I would hope that his wiring did not look like a light bulb filament during operation.