Iwire, the ocp in that residential garage is not going to allow (code-wise) to be loaded beyond 80% so I still don't understand why using a calculation above that amount would ever make any sense. Also, if I were feeding a new garage and it appeared that the load seen would be anywhere near 80% of the 100A ocp then I would install a larger panel (min. 125 but probably a 150 or 200 depending on the customer's future plans and the cost of the related materials). I worked a number of years as a residential electrician and even the most used garages in that realm had a realistic continuous load of maybe 40A (now I am a commercial electrician and that small-load generalization does not apply).
The strange thing is iwire, I think you and I actually see eye-to-eye on this particular issue but go about arriving at the end result completely different. However, I don't believe the end justifies the means when the means have no basis. In other words, you and I may actually wire a given shed identically but I would have data to back-up my claims. Bigger is better as a stand-alone reasoning does not work for me. Also, I understand your frustration with those that "underwire". I live/work in Wisconsin and in 95% of this state anyone can call themselves an electrician. No license is required so you can probably imagine the stuff I run across. Due to the small load it may not be a big issue but residential garages here are almost always fed with #2 Al. While this is OK for the residence itself it is not allowed for the garage associated with it. It is tough for a "real" electrician to compete with these hacks and even harder to explain to an electrically uneducated customer why a larger wire is needed.
