I understand that flipping the main doesn't turn off the power prior to the main.
I intend to add a dedicated breaker for a modest TV/cablebox/dvd/small speaker set where there is no outlet currently. It is upstairs in a set of built-in bookcases. When the house was built, no one could conceive of a TV let alone put one in that area... so there are no outlets. It is very very easy to get to the area from the basement. A few years ago, I had an electrician put in a dedicated 20 amp breaker and single outlet for an air conditioner outlet near this bookcase. so I intend to follow what was done previously with 14 gauge wire and then go past that outlet by about 6 feet. If I can basically duplicate what the electrician did and add a GFCI outlet I think it ought to be ok. I'm always open to suggestions. The TV and sound stuff will be powered through a multi-outlet surge protector used for televisions.
Oh yeah.... when the electrician put in the outlet a few years back, he also made changes to ensure the outlets down in the unfinished basement were tied to GFCIs. I know the ones on the walls were, I am not so sure about the ones mounted up on the ceilings.... but I haven't had an issue with that yet. Everything I regularly use goes on the GCFI circuits in the basement.
If the TV is in the living room, I don't think you need GFCI. They keep expanding what needs GFCI (bathrooms, kitchens, garage, basement and exterior locations) and bedrooms need arc-fault now, but haven't gotten to the living room or den yet.
So I installed 3 single gang surface mount outlet boxes on three shelves in the bookcase. Polarity, continuity, grounding, and operational testing went fine. The next big thing is to wire it to the breaker box.