Florescent fixture draw

[Rusty Bumper]

I am configuring lighting for the shop.
I have 22 hanging florescent fixtures. The plug in type. They read 120 volt.
Each has two 30 watt T8 bulbs.
I thought I would be fine with one 120 volt 20 amp breaker, 12 gauge wire and 20 amp reciprocals across the 14' ceiling.
20 amps x 120 volts x 80% puts me at 1920 watts. The 44 bulbs draws 1320 watts.
Then i see this sticker on the fixture which gives me pause....
If I multiple all my lamps according to this label it puts me at 3300 watts. Which would mean I will need an additional breaker. Correct?

 

[nafterclifen]

Here are my calculations...

120v * .62A = 74.4W per ballast
120v * .50A = 60.0W for (2) bulbs

134.4W per fixture * 22 fixtures = 2956.8W @ 120V = 24.64A TOTAL

If you dedicate (2) 15A circuits, you could get away using 14 wire for the lights but only the lights as 11 fixtures will draw 12.32A which is 82.13% of 15A.

 

[rockwithjason]

you don't use wattage for this calculation, you use the amp rating on the ballast. simply add them up. You can only load a circuit to 80% so use 80% of the amprage of the circuit.

 

[Rusty Bumper]

OK. Thanks. I ran 12 gauge wire already.

 

[cybrdyke]

"Shop Lights", the ones with plugs attached, are not really designed to be used in bunches to light up large spaces, like regular hard wired fixtures. The difference is in the quality of the ballasts and even the lamps. Shop light lamps and ballasts are the worst of the worst. Why? Because they are really meant to be used for task lighting....like hanging over a work bench or a lathe. Manufacturers expect that these lights will only be on for a few hours at a time, and only a few days a month, so the components dont have to last very long....hence the really cheap price.
Fixtures for general illumination of large spaces will be hardwired type. You can get them with crappy ballasts, too, but for the most part, they are a step up from a shop light.
The same fixture you have, in a hardwired version, would be rated at .49 amps and consume 58 watts with the 32 watt lamps... a lot more efficient than the shop light.
I'm not trying to change your mind about your purchase...just trying to help explain the difference.
Good luck
CD

 

[Rookie2]

Did you read this stupid "china" label ! "American Fluorescent " no such animal ! no such "30 watt" lamps they are 32 watts ! The ballast should draw .62 amps though. Reminds me of the dog food poison scam they pulled. .62x22 =13.64 amps total.

 

[Rusty Bumper]

Good to know. Sorry, I meant to write 32 watt bulbs.
I chuckled at the China American Fluorescent tag.

 

[alfredeneuman]

Did you read this stupid "china" label ! "American Fluorescent " no such animal ! no such "30 watt" lamps they are 32 watts ! The ballast should draw .62 amps though. Reminds me of they dog food poison scam the pulled. .62x22 =13.64 amps total.

According to the label

"American Fluorescent", made in China