John,
I have pointed a few folks to Bob Nuckolls site where you will find his book on all things electric in airplanes. The name of the book is The Aero Electric Connection and it is well worth the $25 or so bucks he asks for it. It has become a go to resource that many guys here on this list have adopted.
Take a look at this page http://www.aeroelectric.com/articles.html as it may give you some insight or help. The other thing that helps is to join the Matronics Aero Electric group. When you have an electrical question, it's a great place to go. But Bob's book (in my humble opinion) is the thing to have.
FWIW,
Dan