When I was 13, we added a second story, and my dad and I did all the electrical. 3 bedrooms, bathroom, darkroom, stairway, entry. I did over half the work, with a copy of the 78 NEC close at hand.
Yes, I actually read major portions of the NEC at that time..
Everything was #12 NM, using PT-70 type crimps (the bare copper crimps that look like a .22 short), with lots of electrical tape (my dad didn't like wire nuts.)
I installed a 3-way in my bedroom for the overhead light, a switched outlet for a reading light, and a switched outlet with pilot for the stereo on the other side of the room, with switches at the bedside.
My brother's room was similar, without the stereo outlet.
3 ways for the upstairs and downstairs hallways, stairs, and attic lights.
GFCI for the darkroom/bathroom, GFCI for the entry/outdoor plant lights.
30A 4 wire feeder for the upstairs subpanel, with 3 circuits for the bedrooms/etc, and one stubbed up to a box in the attic for future
expansion.
We even had to replace the service mast to raise the drop to the second story level.. our next door neighbor pulled the meter, and helped my dad move the live drop (our neighbor was at the time a supervisor with the municipal electrical utility, before he retired a few years later.)
Everything passed inspection, except that we never got the final done until my parents finally sold the house 16 years later.. on final, the inspection turned up one(1) outlet with polarity reversed.
I learned quite a bit that summer, and started doing theatrical lighting a year later.
About the only thing I would have done differently, would have been to use wire nuts, and to not use the back-stab connections. We did use Leviton outlets, and not the cheap junk that I see at Home Depot these days..
