Lighting, Light Fixtures, Ceiling and Exhaust Fans - Lighting Circuit Load Question

I am redoing half of my basement and looking into replacing the existing lights with high hats with a drop ceiling. Currently half of the basement I am finishing has about 9 lights. I will probably need about 10 -11 total lights to light it like I would like. My dilemma is whenever the sump pump goes on the lights dim momentarily. I need to double check but I think the basement is controlled by one circuit in the breaker box. I wanted to run a new circuit for the new lighting im planning to install. If you think this is a good idea should I use 14 gauge or 12 gauge and how many light fixtures can I safely operate on one new circuit. Hope this makes sense.

Whenever feasible, the sump pump should be on a circuit by itself.

Flickering lights is generally not dangerous, but can be quite annoying. For this reason, it is best to keep receptacle and appliance loads off of lighting circuits. Let wattage be your guide as to how much lighting to put on one circuit. A 15-amp circuit can handle up to 1800 watts, and a 20-amp circuit can handle up to 2400 watts. To leave some margin, most people try to stay 20% under these numbers.

Since you are doing new wiring in your basement, there's no reason not to do a quality job by installing new circuits where necessary

Hi, John thanks for the reply. I have a couple more questions for you. I will run a new line just for the sump pump. As far as the 15amp and the 20amp circuit. You mentioned the 15amp circuit could handle about 1800 watts and the 20 amp circuit could handle around 2400 watts while trying to remain 20% under these numbers.

Lets say im just using these new circuits for lighting using highhats that use 60 watt bulbs. So based on these numbers let me know if my formula is correct:

2400 watts * 20% = 480
2400-480 = 1920 watts
1920watts / 60watt bulbs = 32 fixtures

Is my math correct or am I not understanding something. So on a 20amp circuit I can power up to 32 light fixtures that use 60 watt bulbs safely?

Also for the light fixtures if I use the 15amp or 20amp ciruit am I using 14 gauge or 12 gauge wire?

Thanks
jd

Your math is correct, although you'll find that must recessed can bulbs are 65 watts.

Use 12-gauge wire on 20-amp circuits and 14-gauge wire on 15-amp circuits. This is true whatever the circuit is used for.