Fluorescent light/wiring question

[bigby]

Got my garage built and I'm getting ready to put in the lighting, I bought several 4ft, 4 bulb lights off craigslist and have a few questions about wiring them up.
The lights have two ballasts in them which say .77 amp and have four 32 watt bulbs, I'm wanting to daisy chain six of them together for each bay in a 45x40 garage with 14ft walls. I figured you would add the two ballast together which would be .77x2=1.54 plus the 4 bulbs which I figured would be around 1.2 amps, so each light would be drawing 2.74 amps and take that times 6 lights would be 16.44 amps. I plan on using 12/2 wire and a 20 amp breaker.
The other problem I think I'm going to have with the lights that all of them are going to draw 49.32 amps off my 100 amp breaker box, the entire garage/rec. room is 40x64 ft, I might have to go with a 200 amp box which none of this hase been put in yet.

Thanks for any help you can give me.

 

[pattenp]

You don't add the tube amps to the ballast amps. You just use the ballast amps. So each fixture uses 1.54 amps. Redo your math before changing to a 200A panel.

 

[pattenp]

Question for you. What type of fixture are those? T12, T8? I assume T8's being the tubes are 32W. The .77 amps per ballast seems high if T8's.

 

[bigby]

I just went and checked, they are T12, the ballast says a line current of .77 amps and there are two per light. Thanks I did not know you were not suppose to to add the lights into the amp usage.
I was going to put 4 lights deep and five rows across in the garage part of my pole barn, but now I'm thinking of three deep? Any suggestions.

 

[bigby]

I just read about T12's not wanting to come on in cold temp. maybe I should buy some T8's instead.

 

[IONH]

I just read about T12's not wanting to come on in cold temp. maybe I should buy some T8's instead.

T8's are more energy efficient. But you already have the T12's so they may be worth considering using assuming they all have bulbs.

As far as temperatures go, how cold are you expecting them to get? I have no issues until below freezing in my garage. Since I don't usually work below freezing, I turn them on and some come on fully while others glow... then I fire up the propane heater and they each eventually come on fully.

 

[pattenp]

I was thinking T12's were 40W that's why I said T8's when you said 32W. Anyway, the standard T12's will be slow coming to full brightness when the the temps get below 60F. Really slow when down to and below 32F. Plus I believe that type of T12 is being phased out, so you may want to do some research on that before you install them. The 2 tube T8 ballast pulls about .5 line amp that's why I questioned the .77 amp you stated. I hope you didn't pay much for those T12's. In the long run you may be better off getting T8's, they are rated for cold starts down to 0F.

 

[regguy1]

I have 2 switches for all my lights (T8's) on 2 breakers, see the setup in the video link below, no problem at all

 

[bigby]

I paid ten dollars a light, and I have 24 of them. I have been reading that you can buy electronic ballast and bulb ends and change the T12's over to T8's cheaper than buying new lights. I found a electronic ballast for forty dollars that would run all 4 lights so I guess I will use the lights and if I have problems I will slowly change them all over to T8. Thanks for all the help, I love this site!

 

[Charles (in GA)]

If the bulb contacts (aka "tombstones") are in good condition and not burned, you don't even need to change them out. I have two of a decorative 4 bulb fixture that originally were T12 with two ballast. I pulled the ballasts out and installed a single electronic GE ballast and 4 of the T8 bulbs and only had to replace a couple of the tombstones that had bad or burned wire connections. (wire connections are push in and sometimes don't make good contact with the wires).

Charles

 

[IONH]

Seems strange if T12 and T8 bulb contacts are the same size as people could easily mix them up.

 

[Delta74]

the tombstones dont really matter, T-12 , T-8 who cares, they all work, usually the only difference is how there wired, T12 ( really old ) often have 2 wires to each, where T8 only have 1, and then you just add a little jumper to the other side of it. lord knows of the 4000 or so ballasts I have changed from T-12 to T-8 we never replaced the tombstones unless they were broken or burned. if you have T-12 now use them till they die, then replace them,tough call on ballast and bulbs only, or new fixture from home despot that has the T-8 ballast. look for sales and consider talking to a wholesale house and just buy a few cases of ballast's, prob cheaper then replacing one at a time.

I would keep the 2 ballast per fixture, and switch them seperatly so there half on, or all on, so you can adjust the light in the garage to suit needs. but thats a personal thing, I like the idea of half of every second fixture lighting on one switch, then second switch again lights half of the all off fixtures, third fires up the rest of the first set, and fourth switch all on, gives lots of different levels of light and power use to match what you need.

 

[pattenp]

Tommy, are you playing parrot?

You don't add the tube amps to the ballast amps. You just use the ballast amps. So each fixture uses 1.54 amps. Redo your math before changing to a 200A panel.

You don't add the tube amps to the ballast amps. You just use the ballast amps. So each fixture uses 1.54 amps. Redo your math before changing to a 200A panel.

 

[bigby]

Thanks for the help guys, I'm going to give the T-12's a try and put T-8's over the work bench. Got to call the electric company to see what I got to do to run power to the garage, I hope they can just split 200 amps below the meter and run a 100 amps to the garage but knowing my luck they will want me to put a 200 amp breaker box in my house and run from it.

 

[nwav8tor]

Glad I found this thread... I was going to buy T12 fixtures for my garage, but now it looks like I'll go with T8 due to better low temp ops, energy efficiency and possiible T12 phase-out.

Thanks,
Paul