Is my math right?

[nissan_crawler]

So, from what I can tell, 14 gauge is good for 15 amps.

With my house at 118vx15 amps that should give 1770 watts.

The lights I'm looking at say 60 watts per fixture (I'm assuming they're talking for the ballast, since it's dual 32w fluorescents?)

I'm putting in 9 of the 4' fixtures in my 20x24, which would be 540 watts, and well within the 80% rating of the 14 gauge.

Am I missing anything?

Before anybody says to just go 12 gauge, I have a 1000' spool of 14-2 I picked up for $20, so I've been using it for all the house lighting, too.

[bmwpower]

I thought you could go 100% on a lighting circuit. Either way, it looks ok to me.

[tfi racing]

Don't use lamp wattage for flourescent light load calculations,use the amps listed on the ballast label.You should be good with 9 ballasts on a 15A circuit.

[Charles (in GA)]

I thought you could go 100% on a lighting circuit. Either way, it looks ok to me.

Lighting is considered continuous load by the NEC. Any continuous loads cannot exceed 80% of circuit protection rating. 20 amp x 80% = 16 amp and 15 amp x 80% = 12 amp.

Continuous is defined as max loads that will remain on for three hours or more. Lighting is specifically defined by the code as continuous.

Charles

[LoneGunman]

Charles is correct but he's still well below maxing out the circuit unless they are older fixtures with magnetic ballasts, then im not so sure. A 2 lamp 4' fixture with 2 f40T12's is only drawing .60-.70A each. I only remember because a few weeks ago I had to do some lighting load calcs.

[ddawg16]

540W....That is less than 5 Amps....yea, ur good to go....

As for the lights.....60W...I'm betting that they use the newer 32W bulbs....which should be 64 W....but if you round it...60W is close enough....

Let us know if you can listen to the radio with the lights on....

[Nealcrenshaw]

sounds right,double check the sticker and make sure the total watts are correct

[trainer]

I put in 18-2 lamp, 4ft t-8 fixtures on one 15 amp circuit. The ballasts are marked 0.49amps each.

[Aceman]

Let us know if you can listen to the radio with the lights on....

I bet if the members on here spent a little more money on fixtures instead of buying the cheapest thing they can find(which includes the economy grade ballasts made just for HD) they wouldn't have that problem.

Think about it: You know how many office buildings are wired with thousands of T8's, that don't have a problem with radio interference?

Clearly, it has to be a ballast issue. Either replace the fixture or replace the ballast with a quality one from an electrical supply house.