It sounds as though you have corrosion or some other resistance in the
circuit. I would check for a voltage drop across the circuit breaker and
switch
while the circuit is under load.

Bingo.
voltage drops to about 0
played with it enough that the circuit breaker started popping
corroded terminal on the switch/lead to the circuit breaker

hooked a battery direct to the pitot heat terms and it works fine

will try a new switch & lead tomorrow

thanks all!

Jim


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