Lighting Circuit Size/Design

[matt_i]

Just wanted to kick around some numbers, I'm doing the homework for my electrical rough-in. Initially wondering if a 15A circuit @ 14/2 awg can support the full demands.

I was just adding up wattages here of proposed devices.

4pc T5HO 4-bulb (54w/tube) x 4tube/fixture x 4fixtures = 864W

2 yard floodlights (lowes utilitech 65W CFL) = 130W

4pc attic bulbs, 22W CFL screw bases = 88W

10 (or so) soffit LED downlights, 8W each = 80W

8pc CFL overhead screw-in bases, 22W each = 176W


Total = 1338W full demand, everything on at once. Equates roughly to 11.1A on 120vac.

I believe based on the above, I'm OK to run with a single 15A circuit, and distribute as needed to the various locations. Your thoughts? Thanks!

 

[dave*99]

Does this represent all the lights in your (I assume it's your garage) project? If so, when you turn that breaker off will you be in complete darkness?

 

[nadogail]

IMHO, your calls show that 14 will be adequate, but very little room for expansion (expansion is a given, it will come).

If you install 12 gauge wire, you will have lots of options for future growth.

My advice is guaranteed, if I am wrong I will refund every Penney you paid for it.

 

[matt_i]

Your point is very good, but I thought of the reason I was trying to stay with 15A circuit...if I feed with #12, I have to run #12 throughout the entire circuit, in order to protect all of the downstream conductors. Just trying to make my life easier in terms of pulling wire

 

[dave*99]

Your point is very good, but I thought of the reason I was trying to stay with 15A circuit...if I feed with #12, I have to run #12 throughout the entire circuit, in order to protect all of the downstream conductors. Just trying to make my life easier in terms of pulling wire

Perhaps two circuits (15A each) would work for you?

 

[tarmy]

I learned the hard way not to push loading a light circuit near the 80% capacity...you WILL ADD LIGHTS!!!

Do yourself a favor and run 2 20 amp 12 ga. circuits...you will be happy you did..

.View attachment 552101

I have twenty five T5HO four bulb lights in my shop...***** power ...but I can see...this is a crappy picture...but the conduit on the ceiling shows that I had to go back in my new shop and run more circuits...oh well...

 

[BADSIX]

i'm defiantly no electrician wizard but i'm going though the same thing. but I think when you figure your wattage for a fixture you need to go by the rating of the fixture. like your soffit lights the leds are rated at 8w, but the fixture is rated at say 75 w that's what you go buy. what if you put 8 w bulbs in now and later someone puts 75 w bulbs in . I would go the 20 amp. 1920w as compared to 1440 w this is how I was told by an electrician
Jay D.

 

[matt_i]

Good point, but these are dedicated LED pots @ 8W with a driver, no retrofit possible. On the 22W CFLs, someone else down the road could theoretically put in 200W incandescent bulbs into every single fixture and draw 2400 watts vs my planned 264W. In theory that would drive a 20A circuit just for 12 screw-base sockets loaded to 100% and nothing else. That's pretty conservative, also I'd be planning for someone else's idiocy...I guess the way I see it is eventually my breaker will trip to protect the conductors if it was to be overloaded, or they would go broke trying to fuel the glowing tungsten.

I have only a couple more slots left in my 60A main lugs mini-load center that's "integrated" into the walls of the existing shop (I'm adding to the existing shop). There is a surface mounted 100A panel in my shop for feeding air compressor, welders and a dozen machine tools, and the 60A is a sub of my 100A sub now. Trying to keep the 100A panel such that if I ever were to move, it & the THHN in conduit goes with me, the original 60A feeder (abandoned in place) gets put back, and I setup shop somewhere else with a pile of materials I don't have to re-buy