Thank you for the informative responses to my question.  I learned something, thank you.

The most important thing I learned was that I didn't need to ask the question in the first place!  I am using an EXP2Bus secondary power distribution system from Control Vision.  This board has 10 amps available on the bus that is energized when the master switch is turned on.  (Large loads, such as landing lights, strobes, fuel boost pumps and such that you expect to have available with the master on have their own circuits, so there's actually more than just 10 amps available for the aircraft.)

I thought that the voltage regulator counted as part of the 10 amps.  It turns out that there is a separate 5 amp circuit for this, so my question has been rendered "of academic interest only".  But then, being basically an academic, I found the answers fascinating.

Thanks.

- Rob Wolf