Bob,

I like it! A no load voltage drop test, an oxymoron [Linked Image] I'll bet the quality of your wiring wowed 'em.

Sparky & George,

I did a calc on 5% drop, 120 V, 12 A load (80% of 15) and I get

#14 solid = 81.4' of cable
#12 solid = 129.5' "
#10 solid = 206.6' "

Thinking more, this afternoon, I suppose placing a 100 VA load on each of my hypothetical 18 outlets and then measuring the voltage at the farthest outlet down the cable run would be the most accurate.

I find it interesting that the NEC Handbook says 210.19(A)(1)FPN No. 4 is
Quote
a warning about improper voltage due to a voltage drop in supply conductors

Al Hildenbrand