HO lights are not supposed to be mounted flush to the ceiling. The ballast gets too hot. Hang them from a chain, one chain on each end. The fixture vendors even provide a specialized wire hanger bracket shaped like an upside down Vee. There are holes in the side of the fixture (at each end) for the bracket to fit into.

Hanging the fixtures should reduce the hum quite a bit; your metal ceiling makes an excellent sounding board.

Making sure the metal fixture is solidly grounded also helps -- cheesy two wire extension cords will make them hum that much worse.

Nothing will cure the hum of cheap Chinese "Shop lights", especially in cold temperatures. Also, magnetic ballasts, even the "energy saving" ones, which are designed for residential use will hum in protest if you try to operate the lights below 60 degrees F.

 

By 14' walls, you mean the ceiling is at 14'? At that height, fluorescent strips are at their limit. You'll need quite a few lamps, T8, T12, HO or otherwise. If I was lighting a shop with a 14' ceiling, I'd seriously think about metal halide fixtures.

www.e-conolight.com has some nice, affordable options.

 

14' is nothing for high output flourescents. at 14 foot you could use low bay metal halide fixtures but they would hang down at least 16 to 18" and you would lower your clearance. plus you would end up spotting too bad with them. they make some very high output light fixtures to replace the metal halide high bay lights to save money and actually increase foot candles.

 

I don't know who makes them, but where I work, they replaced the metal hallide 3-phase lights with 8 foot flourescent fixtures that hold 16 tubes. These things are way brighter. They sit about 20 feet or so in the air. The hum is grounding.

 

It really depends on the fixture. A standard 2-lamp HO strip is not ideal for a 14' ceiling in a shop. I've spec'd them at higher elevations, but usually in continuous rows and for warehouse or mechanical spaces where the required lighting levels are lower. Personally, I like a shop to be bright. Our lighting reps have been pushing multi-lamp HO T5 fixtures to replace HID's for years. However, they can't beat the lamp-life and reduced maintenance (1 lamp vs. 4, 6 or 8) of HID's. For my clients, maintenance costs (lamps and labor) are sometimes the most important factor. Plus, comparible HID's can be cheaper up front.

Also, the fixture I thought about for my 10' ceiling is a totally enclosed surface mount 175W MH that e-conolight sells for $90 each. It would hang down less than chain-mounted strips. However, for my application it's tough to beat the $20 2L T8 strip (with grill) that Home Depot sells after I ran the calcs.

It really depends on the application. I'd need more information about the space to say more.

And as long as I'm blathering on about lighting, if you have T12 fixtures in your shop and keep burning through 34W bulbs, you may have older fixtures with ballasts designed for 40W lamps that won't push a 34W lamp. I ran into this issue and have been slowly swapping out the T12 fixtures for T8 versions as the lamps die.

 

The hum is grounding.[/QUOTE]

Some say it's the ballasts that hum, you say grounding. Please explain.

Thanks: BuffDaddy

 

When the T12s and T8s are side by side, do you see much of a difference? I am curious if the light output is noticable.

People should be careful with mounting lights up against the ceiling. I saw one ballast that did a mild explosion overnight. I went to replace the thing and the ballast had burned a small hole through the top of the metal fixture and literally spotwelded itself to the hole. I went around with my laser spot themometer after that and checked the others. That's a handy tool and the price is dropping.

 

F32 T8's are comparible to F40 T12's... maybe even a tad brighter... but considering the T12 fixtures are over 20 years old, it may not be a fair comparison. The narrow light source is supposed to make the reflector to worth better, although with industrial-strip fixtures, I personally don't think it matters as much.

Even better: no hum and instant light no matter how cold (at least in New Jersey). Once temps dipped down to near freezing, the T12's dimmed considerably.

Installing 34 watt T12's in the 40 watt ballast fixtures was a waste of time... very dim... and basically worthless when cold.

 

Whatever light you go with, be sure to put each row on a seperate switch.

We put up 5 rows, 4 each row of 8' T12 shop lighting (home depot) and just turn on what we need for which ever side of the shop we're working in. Our eve's are 18' and I believe we're at 22' at the peak. When we turn on all 5 rows it's like daylight in there. Shop is 40 deep by 50 wide (bigger than my house).

We also hung ours with chain, about 1' lower than the beams.

 

Well, I got all my lights today, some good lithonia fixtures from Platts. I want to send out a big thanks to fefarms who help educate me on lighting, help me pick out my stuff, and then got them for me at his discounted price at Platts. I've only got two of them wired up so far but the light they give off is awesome! Thanks again

 

You really should have planned GTG's around this project..

 

No doubt!!!!! We are really waiting for some pics in the chapter forum Pro.....

come on, please!!!!!

Had I known about this thread before today, I could have helped too, My folks own Phoenix electric on division, and my brother works the counter on the contractor side, Spokanes a ways away I guess, but oh well.

Glad you got er figured out

 

Well, I don't know if you noticed in the "whoa" thread but my digi cam recently broke, so I don't have a way to put up pics. But if I don't get a new one in the next month I'll have Ivan snap some pics with his when he's up next month.

 

Yes, I just got an email about the whoa thread and put two and two together

 

for placement of the lights i would suggest go to a body shop of good reputation and see how they set thier lights up. if they do good work they must be able to see what they are doing.