I think I figured it out; although I'm still a little confused why the Code doesn't spell it out a little clearer.
I understand that service conductors are not protected from short circuit and ground fault overloads like branch circuits and feeders are but Part VII of Article 230 is dedicated to the overcurrent (overload only in this case) protection of Service Equipment and Conductors.
Specifically, 230.90 (A) "Where Required. Each ungrounded service conductor shall have overload protection. Ungrounded Conductor. Such protection shall be provided by an overcurrent device in series with each ungrounded service conductor that has a rating or setting not higher than the allowable ampacity of the conductor."
If we go look at 230.42(A)(1), the conductors are sized according to the 125%/100% rule and since the overcurrent device is selected based on the conductor size, indirectly the OCD is sized using the 125%/100% method.
Does that sound about right?
The way I see it. When it comes to finalized the size of your Service conductors this is the following:
a. Lighting is at 100%
b. General Receptacles is the first 10kva at 100%, the remainder is at 50%.
c. AC Units are at 100%.
d. Motors, Pumps, can take a diversity factor.
e. Elevators, there are factors in the Code that you can take.
f. Laboratory, requires a little thinking in using demand factors
and the final solution is a simple adding.....
I hope this will help......
