I am finishing-out my basement and am now roughing in the electric using 12-2 Romex. I am planning on adding two 20 amp breakers to the service panel and want to make sure that the breakers, and the Romex, have sufficient capacity for the room. The service panel is also in the basement, located about 5 feet from the room.

Lighting. I plan to run 10 recessed lights using 100 watt bulbs, broken into three different runs for switches. I also plan on having at least 3 75W wall sconses and 2 60W lights over the bar.

Outlets. I'd like to have as many as 10 outlets. The main power load will come from the home entertainment system, (stereo, vcr, dvd, projection tv), and a mini-fridge.

How do I determine the max safe capacity?
Can, or should, I run all the lights on one and the outlets on another?
What else should I be considering?

Thanks in advance.

 

First, make sure you're using cans rated to take 100-watt bulbs before you install such high wattage. Cans have a thermal cutoff that will turn the lights off if they get too hot.

There is one key piece of information you omitted, which is necessary for a good assessment. How many square feet is your basement.

You have identified 1345 watts of lighting. This will certainly fit on one circuit. Your ten receptacles will also fit on one circuit. I would divide the loads this way, one circuit for the lighting and one for the receptacles.

Before going futher, I would add up the wattage of all that electrical equipment and refrigerator. Post back with what you come up with. Although your plan seems reasonable, it has no room for the future. You are starting out with both circuits fully loaded. Consider what you might be adding later -- more lights, a computer, more home theater equipment, possibly some space heating for a chilly evening.

Please tell me how many square feet your basement is, and the wattage of your electronics. Are you finishing all of the basement -- if not how many square feet will be left unfinished? Besides the home electronics, what other activities do you plan for your basement, and how many different people might be using the basement at the same time? All these factors will influence your power requirements.

 

John:
Here are the details and background info. At the end of the post I have an additional question or two.

I checked the cans and they can handle from 75W to 150W depending on the bulb and trim used.

The total finished square footage is 340SF, 290SF in the room itself and 50SF in the hall. There is an additional 200SF unfinished workroom which contains the HVAC, water heater and service panel, (and my power tools).

Most of the electronics listed the watts, but several did not. Here's the skinny:
Onkyo Receiver - 120v - 4.3amps - 60 Hz
JVC DVD Player - 20 watts
Cassette Player - 32 watts
Sony VHS VCR - 33 watts
Projection TV - 120v - 3.0 amps
Cable box - 13 watts
Mini fridge - Not sure, we haven't bought it yet

Optional Equipment
Small TV - 100 watts
Blender - 350 watts max

Here are my questions and concerns:
I added up the breakers in my service panel for a grand total of 480 amps on a 200 amp main breaker. The only breaker added after the original install was for the hot tub, and was added before I bought the house.

There physical room in the panel for 2 or 3 more breakers but is there capacity to handle them?
Or is the panel already overloaded?
If so, can I add a sub-panel to carry the additional load?

Silly me, I thought finishing the basement was going to be easy!!

Thanks again for all your help

 

Whoa! You mentioned the words "workshop" and "power tools". This may change the picture considerably Depending on what you have, these tools may use more power than everything else combined.

Adding up the breakers in a panel is a meaningless exercise. Don't give another minute's thought to why your breakers add up to 480. It doesn't mean anything.

Capacity can only be computed by a demand load calculation. This calculation is quite involved and considers just about everything in your house. However, since you have a 200-amp panel, it's reasonable to guess that you're okay (unless you have a very huge house, or some very power-hungry hobbies). 200 amps is enough for just about everybody.

With only 2 or 3 spaces left, I'd recommend that now is the time to add a subpanel. You can add a small subpanel in your basement (using 2 of the remaining spaces in your panel), and then you'll have plenty of flexibility to your basement. A subpanel is neither difficult nor expensive to add. About four circuits could then be added in the basement, and you'd have room for even more in the future. I'd put in a 40-amp double-pole breaker in the main panel and run 8/3 cable to your new subpanel. That gives you 9.6KW of power for your basement -- should be plenty.

 

Thanks for all your help.....you're almost done.

If I add a 40 amp breaker on the main panel, can I use 4 20 amp breakers on the sub panel? I figure one breaker for the lights, one for the outlets, and one for the bar area (fridge, blender, etc). and one for expansion.

Since there is minimal existing wiring in the basement, I'll either need to tie it into the design, or cap and plate it off. Even with all your expert advice I've still got a bit of noodling to do.

The "workshop" includes a table saw, miter saw, jig saw and wet/dry vac. But as a week-end warrior, doesn't get a tremendous amount of use.

It looks like this week-end may be it for the big install. I'll post back my success story when I'm done!!

Thanks again for all your time and advice.

 

If you feed this with a 40-amp breaker in the main panel, you can easily add more than four 20-amp breakers in the subpanel. Keep in mind that the 40 amps will be at 240 volts, and the 20 amp circuits will only be at 120 volts. Combine this fact with the fact that all circuits are never fully loaded at the same time means that you could easily have 6 or 8 20-amp circuits in the subpanel with no problem.

I'd devote one circuit just for your workshop. The rest of your plan sounds fine. Remember that any receptacles in unfinished areas of your basement require GFCI protection. And be sure to keep the neutrals and grounding wires isolated in the subpanel. Get a permit and make sure the electrical inspector looks at everything carefully.

 

The breaker for the sub-panel finally arrived by UPS. I had to special order the 50 amp breaker since my panel is 20+ years old and no-one locally stocks replacement parts.

As a potential sub-panel, Lowes has a 100 amp panel with main breaker, with 5 20 amp and 1 30 amp single pole breakers as a complete package. Can I use this as a sub-panel? Is there a better solution?

 

It's just never as easy as it seems....

I just bought a Cutler-Hammer BR LoadCenter (125 amp) tonight at Lowes to use as the sub-panel. When I opened it up, in addition to the hot bus bars, it only has one other bar, presumably for the neutral.

Do I hook the grounds up to the same bus bar as the neutrals or do I have to order a second bus bar for the grounds?

(FYI: You know the electricians I talked to quoted me $1,800 for the entire project, I'm starting to think it might have been a good investment.)

 

Just go back to Lowe's and buy a ground bar for your panel -- about five bucks. In the subpanel, you need to keep the neutral wires isolated from your subpanel's case, and from the grounding wires. If you look at some other brands of panels, you'll see that they come with two bars already installed, one mounted directly to the panel and one mounted on a plastic insulator to insulate it from the panel. Remembr, the neutral bar (with all the white wires connected to it) must be isolated from the panel, and the grounding bar (with all the bare wires connected to it) must not be. And you must not install the screw that bonds the neutral connector to the panel.

 

I'll head to Lowes tomorrow to pick up the grounding bar.

When I hook up the breaker to the main panel, the black and red both go to the breaker, the white to the neutral bus and the bare wire to the ground bus?

Thanks again John. I really appreciate all your (and WG's) help through this process. The Forum has been a life saver.