garage lights

[mike's48]

Hey folks,
Im wiring my garage now all 20 amp from a 100amp/24 cir panel , but i need to know how many 8'-2 tube floresent fixtures I can install in a series from one switch. I would like to run 4, (total of 32'end to end) I will be having this inspected so it must be right. Your help would be appreciated.
Mike

 

[e-tek]

I have 10 on my ceiling on one switch and I have a feeling its MUCH higher than that.

 

[pattenp]

My understanding is that you don't want to exceed the amp rating of the circuit by more than 80% which on a 20 amp circuit would be 16 amps. As an example if each fixture draws 1.6 amps then you could have 10 fixtures max. You need to see how many amps each fixture pulls.

 

[CalGeo]

PATTENP gave you a pretty good answer, but you should check the amperage of your ballast to confirm that he is correct. We don't know what type of fluorescence lights you are are using nor do we know if you are using an inductive ballast or electronic ballast. The amperage rating will be on the ballast.

I used two rows of (2) f96ho lamps set at 10' on each side of my work bay and have plenty of light and when I want more, I turn on the (5) 400 watt Metal Halide lights that are set at 13' .......nice

 

[larry4406]

My 28x50 by 12 foot tall garage has 16 T8 fixtures, 2 bulbs per fixture, fast start (don't know the specs, they were new, free and I hung them fast). The end single bays each have 4 fixtures while the middle double bay has 4 rows of 8 fixtures (two each ganged together). I used a 15 amp circuit on a 3-way and all come on together. Forgot the kelvin rating of the bulbs but very bright and works well with the white ceiling and white walls (walls are blue up to about 5 feet, then white above).

A 15 amp 110 volt circuit could in theory accomodate 1650 watts (15x110). My fixtures use 32 watt bulbs so the total bulb wattage is 1024 watts (32x2x16). Thus, the circuit is at 62% of capacity. This was my logic since I did not have the fixtures at time of wiring. As stated previously, the math really should consider the efficiency of the ballast and use the ballast amperage times 110v to get the true fixture load. My understanding is that circuits should be planned for no more than 80% of capacity, so I judged that the ballasts would not take me from 62% to 80%, as that would be horribly inefficent ballasts. It works for me, your mileage may vary.

 

[mike's48]

You guys are the best! Thanx for all your help
Mike