The second new requirement in 200.4(B) is that you cannot combine neutrals from different circuits.
I one had the honor of paying for the $600 worth of damage caused when I failed to properly connect all the neutrals under a nut, and one worked loose. In that instance, the original installer had run out of room in the pipe back to the panel for all the wires- and the one that came loose resulted in 200+ volts on a 120v circuit. Oops. I have not liked putting 8 wires under the same big wire nut ever since!
Seriously, though .... this change forbids my solution to a similar pipe-fill issue. I had a house re-wire, where I was able to run only 1-1/4" pipe from the panel into the attic, where all the new circuits terminated. My solution was to place a gutter in the attic, and run all the circuits to the gutter. Inside the gutter I mounted a neutral bar and a ground bar. Thus, to the panel I only had to run one (larger) neutral and one (larger) ground. Each 'hot' continued to the panel.
I think it's foolish to try to reduce the trade to only "simple" solutions. There's a place for the professional to actually design things; we're reduced to 'cookbook' approach.
I suspect all these 'problems' are only being discovered now, because -after a century of electrical work- we're seeing a new class of inspectors, plan reviewers, managers, etc. who have only 'book' learning, and have not mastered any trade. We're being governed by the ignorant.
