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# circuit capacity

## circuit capacity

#1
06-15-14, 09:34 AM
Member
Join Date: Jun 2014
Location: usa
Posts: 2
circuit capacity

I have between 12 and 15 flouresent light fixtures, they each have 4-40 watt bulbs and two ballast per light. I want to know if I can run all of these off of one 15/20 amp breaker, they are all T12's and they are the lights for the recessed ceilings.Thanks

#2
06-15-14, 09:49 AM
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Join Date: Oct 2012
Location: Jersey
Posts: 64,590
Welcome to the forums.

You need to look at the ballast to get the actual running current.

To figure out load per fixture..... 40+40+40+40=160w plus each ballast.
You'd be looking at approx 1-1/2 amp per fixture.

#3
06-15-14, 09:54 AM
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Join Date: Nov 2007
Location: United States
Posts: 14,269
Welcome to the forums!

Sorry but the lights are too much for one circuit. You can only load a circuit to 80% continuous load (more than 3 hours) which gives you a max load of 16 amps for a 20 amp circuit, or 12 amps on a 15 amp circuit.

To calculate the load you need to take the info off the label of the ballast, not just the lamps. IIRC a 4 lamp T12 light fixture draws about 1.5 amps each. So at only 12 fixtures you are at about 18 amps.

You need to use two circuits. If you must run them on a single switch, you can install a two pole switch, or just put them on two switches.

Your other option would be to convert them to T8 ballast and lamps. However, that would cost around \$300. Good side is they would give more light while using less energy. Also T12 lamps are being phased out.

#4
06-16-14, 08:01 AM
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Join Date: Jun 2014
Location: usa
Posts: 2
T8 or T5

Thanks for that information, I will run two circuits. I went to the supply house too check prices and the man there seemed to know what he was talking about, he said that if I was going to change I should go with T5 they would be better and cheaper to run in the long run.

#5
06-16-14, 06:03 PM
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Join Date: Nov 2007
Location: United States
Posts: 14,269
T5's have even more savings than a T8 when compared to T12's. Although they are more expensive on the front end and they have not become as mainstream as T8's. However, in July, T8 700 series lamps will also be discontinued. 800 series will still be available.

I suspect Florescent will be taken over by LED in the next 5-10 years so I think T5's will be passed over.