[matthewb]

I am in the process of finishing my previously unfinished basement. I've got all the framing done, and it's time for electrical before I get to drywall.

My basement is very small, and there will simply be a den, and a bedroom.

There are two 15amp circuits running to the basement currently.

The first circuit has a single outlet on it, and that is it. It was run with a LOT of extra 14/2 wire, so I assume this was put in anticipating that some day somebody might want an extra circuit down there.

The second circuit first runs to all of the smoke detectors in the house (5 of them) before heading down in to the basement. It splits up behind a light switch and heads 3 directions.
1. 14/3 wire to a dual switch light in the stairway.
2. 14/2 wire to four simple overhead lights.
4. 14/2 wire to two outlets, one of which runs the phone switchboard, and the internet router.

To the first room (the den), I want to add 4 wall outlets, and replace the 4 overhead lights with something a little more attractive... probably track lighting once I drywall the ceiling.
I want to have the lights for the second room separate from the lights for the first room, so obviously I'll be adding a wall switch and some 14/3 somewhere in the process.

So here are the direct questions.
1. Is it better to run one circuit to each room, or is it better to run all lights (2 rooms) on one circuit and the outlets (2 rooms) on another?
2. Do I need to upgrade one/both circuits to 20 amps? (I've noticed my circuit breaker has no free slots)

I've done work with home electrical before, but I've never been the one doing the planning, so any help or advice would be amazing!

[tkrussell]

First off, the bedroom lights and outlets will need to be protected with an Arc Fault circuit breaker, so this answers having two circuits, one for the den and one AFCI for the bedroom.

Other devices in the den can be on the AFCI circuit, as long as all the bedroom is protected.

You will need to check with local codes thou. NEC requires smoke detectors on AFCI,however, many states have modified this to allow smokes to not be protected. You will need a one detector in the bedroom, along with at least one elsewhere in the basement level.

15 amp circuits for each is fine, a 20 amp may be good for the den if you plan to have any large or constant loads, like dehumidifiers, space heaters, etc. Otherwise 15 amp is OK.

[labman]

You really need to add the breakers as tk says. You can make room for a few more breakers by replacing some of your breakers with the ones that provide 2 breakers in one slot. I doubt the AFCI ones come that way, so you will have to do some rearranging.

An unrelated suggestion is to carefully seal the basement up before finishing, caulking around the plate and band joist. Also around all the pipes and wires. Warm, moist air can flow up along pipes clear to the attic, where the moisture can cause problems. Seal the pipes and wires in both the basement and attic.

[matthewb]

NEC requires smoke detectors on AFCI,however, many states have modified this to allow smokes to not be protected.

There is already 1 detector in the basement, and I can easily add another.

Both of the 15 amp circuits to the basement share a slot in my circuit breaker, so if one is AFCI, then they both probably are.

If it is possible that the circuit is already AFCI, how can I check?

[tkrussell]

I attached a picture of a typical AFCI breaker, looks similar to a GFI breaker, they all have test buttons.

If your panel is full, with no more than 42 circuits, then you can do as Labman suggested, get half size or tandem breakers for some of the other circuits. These allow two breakers in one 1 " slot.

You probably don't have an AFCI breaker, unless your home is fairly new. They do not come in half size, so that's why you will have to change out other breakers to make room for the new AFCI.