According to :
Folks:

My copy of the NEC doesn't actually restrict the voltage drop for
residential
wiring, but recommends a 3.6v drop in the branch circuit and a 5v drop
including
both branch and feeder together 'for reasonable efficiency'. Seems to
me a
circuit coming right from the panel could use the 5v value. These
are both
for 120v circuits, by the way. (3% and 5% are the values given, I
think. I don't
have the book on me right now)

When I wrote the electrical wiring FAQ, I believe it went this
way in the NEC: you were _permitted_ to have as much as a 5% drop
on a circuit, and the utility is similarly required to provide
you 240V at the panel +/- 5%. Which works out to the voltage
at an outlet being permitted to be as much as approx 9-10% less
than nominal.

Which is where the nomenclature of "110V" came about - the minimum
permissible outlet voltage given permissible voltage drop from
the nominal supply voltage.

This is not to say that you can't engineer _better_ than that.
Eg: circuits driving 1/4HP+ motors should be carefully considered
for example.

But a maximum 15A circuit run of 30' for #14 is ridiculously
short. You'd hardly get to use "normal wire sizes" anywhere
in a house, you'd almost always be derated a size or more.

[My calculations were based on 1 ohm/1000'. I misremembered, it's
2.575 ohms/1000'. #10 is 1.018 ohm/1000']
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.