Question Regarding Full-Rated (100%-Rated) Circuit Breakers
I found this excellent blog from Schneider Electric on the differance between 100% rated and 80% rated breakers. This is a link to the Podcast mentioned in the blog.

Clearing up Confusion over 80% vs. 100%-rated Circuit Breakers
Paul Desmond | June 12, 2014

When building or upgrading a data center, at some point you need to
make a decision about which circuit breakers to use. While on the face
of it that may seem to be a simple decision – use the one that’s the
best fit for your load – in fact it can become significantly more
complicated if you don’t have a thorough understanding of breaker
ratings and what they mean.

In the circuit breaker world there’s been some misunderstanding about
the terms “100%-rated” and “80%-rated” circuit breakers. To dispel the
confusion, Schneider Electric’s Mohamed Shishani put together a short
(less than 10 minutes) podcast that does a nice job explaining the
issue.

Understanding the difference between the two begins with a reading of
the 2011 National Electric Code. Section 210.20(A) of the code
basically says that a circuit breaker for a branch circuit must be
rated such that it can handle the noncontinuous load plus 125% of the
continuous load. (A continuous load is one where the maximum current is
expected to continue for 3 hours or more.) In other words, the breaker
needs an extra 25% capacity of the continuous load for headroom. That,
of course, means you need a larger, more expensive breaker.

There is, however, an exception. When the circuit breaker is listed
for operation at 100% of its rating, the additional 25% requirement
goes away. Instead, the device simply has to be able to handle the sum
of the continuous load and the noncontinuous load.

Now, in practice, you may think it will nearly always make sense to
buy 100%-rated breakers and call it a day. But as the podcast points
out, it’s not quite that simple.

You need to do some load calculations to determine if your loads are
primarily continuous or noncontinuous. If all your loads are
non-continuous, you don’t have to worry about the 125% requirement so
you can just size your breakers for 100% of your load. In that case,
standard, 80%-rated breakers will be more economical.

If you do have some continuous loads, Shishani says it’s best to
segment your circuits so they’re all the same flavor, either
continuous or noncontinuous. Then the choice of breaker will become
clear.

Where you can’t do that, you need to determine the load on each branch
circuit, then calculate the required ampere rating you need for each
circuit breaker. The rating will be higher for the standard, 80%-rated
breakers because you need to allow for an extra 25% capacity on the
continuous loads. That may make the 100% breakers the more economical
choice. On the other hand, if you need room for growth, that may also
play into the equation.

The podcast goes through a few sample calculations to help you
understand all the tradeoffs. Check it out to see if you can save some
money the next time you need to buy circuit breakers.