Comment on Affirmative:
CLINE,
S.: This proposal is the result of many, many hours of panel member
time over many code cycles. It is intended to clearly and easily express the
ongoing intent of the panel over these many code cycles of misinterpretation.
This wording gives a simple ?duty cycle? type adjustment which, through a
simple mathematic multiplication, yields a minimum ampacity requirement for
conductor sizing. Hopefully the twelve submitters who also spent their time
trying to resolve the misunderstandings will be satisfied with this result.
It
recognizes the long-known diversity of load for this exact class of load. It
recognizes that conditions of installation may also affect the ampacity of the
conductor. It recognizes that feeders, only if sized in relation to the service
rating, may safely be allowed the same diversity adjustment since they are
either carrying 100% of the diversified load, OR only loads too small to change
the effective diversity have been removed ahead of the feeder, OR large enough
loads have been removed ahead of the feeder to make the 17% adjusted
ampacity a moot point. The concerns about increased dwelling loads in general
is addressed in 230.79 where the service rating amperage itself is determined.
It
should now be clear that while feeders may also use the diversity
adjustment, it must be based on the 230.79 service rating, not the size of the
OCPD for the feeder. If you run a 200 amp feeder from a 200 amp rated
service, you get to use the adjustment, start with a 166 minimum ampacity
conductor, apply any other required adjustments, and choose your conductor. If
you run a 100 amp feeder from a 200 amp rated service, you still get use the
adjustment, but of course the 166 minimum ampacity conductor then required
might not be an advantage over the normal 100 amp conductor. You may not
use 100 amps (the feeder OCPD size) to apply the adjustment to - you must use
the service rating.