[SilverStreak] Electrical question

["Bussiere, Curtis L SFC RES USAR TRADOC" <curtis.bussiere@xxxxxxxxxxx>]

I have never totally understood the theories behind the limited supply of 110 
power throughout our 74 SS. Why some outlets only work with the transformer switch 
on and others work with it off. If someone can give me a laymens explanation I 
would appreciate it.
My main question is where would it be best / safest to tap into a 110 source? I 
have installed a new ceramic lined hot water heater and it runs on gas or electric. 
I can handle the installation of all except the electrical. I have a friend who is 
an electrician but knows little about campers. I dont think I could find or afford 
a good camper electrician so I want to direct the guy to the most reliable source 
for 110 on the SS. Should we go through the transformer or directly through a breaker?