Troffer retrofit switching issue

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Old 04-24-13, 05:53 PM
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Troffer retrofit switching issue

1. Would an old three-bulb T12 troffer have had two ballasts, or what?

2. Would a two-bulb T8 retrofit kit use a single ballast for both bulbs?

3. What would a lighting contractor do if customer specified switching so just half of each fixture could be on if desired?

Background ...
The office hired an energy management contractor to save big money ... the contractor guarantees lower energy payments and more or less takes a commission.

Here's the issue. The old 2x4 troffers had three T12 bulbs each. In most areas they were configured with the two outboard bulbs on one switch and the inboard bulb on another switch, so the occupants could select 1/3 lighting, 2/3 lighting or full brightness.

Now they are replacing the reflectors and ballasts with retrofit kits that have two T8 bulbs. They are switching by row rather than 1/2 of the fixture on one switch and 1/2 of the fixture on the other switch. So now for example if an area has three rows of troffers, they put the center row on one switch and the outside rows on another switch. This means a choice between some work stations having full brightness and others having no direct lighting, or all lights on, which is causing consternation as most people preferred 1/3 or 2/3.
 
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Old 04-24-13, 06:18 PM
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An old three tube fixture would have two ballasts. A single lamp and a dual lamp.

Yes.... a single ballast can be used for one, two, three and even four tubes. Would need to be specified when purchasing.

The contractor would need to install two single lamp ballasts to have the lamps individually switched.

That would increase the cost of the retrofit significantly... two ballasts per fixture.
 
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Old 04-25-13, 06:49 AM
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Thanks. So without upgrading to more expensive kits, would these admittedly impractical workarounds work:

1. Adding wire to ballast leads so one set of leads would reach to adjacent fixture.

2. Removing one bulb from each fixture.
 
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Old 04-25-13, 08:17 AM
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Removing a bulb is about the only option. Adding a second ballast or jumpering fixtures is either adding expenses or impractical.

Too late now, but this all should have been worked out before the retrofit. It does not sound like the work was well thought out or understood. There is no way I would have suggested the result you ended up with.
 
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Old 04-25-13, 08:23 AM
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I've read this three times and I'm trying to figure out how removing a lamp will accomplish what you want.

If this is an office or working environment.... I don't see why all fixtures wouldn't be left on.
 
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Old 04-25-13, 08:04 PM
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PJ, the fixtures now have all 3 lamps on all the time. For some this is too bright, but the way they are switched results in some sitting in the darkness while others are under full brightness. Before there were differing levels of light from all the fixtures ie one bulb on, two bulbs on or all bulbs on in all fixtures. The flexibility has been lost.
 
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Old 04-25-13, 08:11 PM
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Now they are replacing the reflectors and ballasts with retrofit kits that have two T8 bulbs.
I understand that before the conversion there are/were three lamps BUT after the conversion there will be only two T-8 lamps...... or do I have that wrong ?

We've done the same conversion and usually the two T-8 lamps is an ideal lighting level.
 
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Old 04-25-13, 10:01 PM
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I understand that before the conversion there are/were three lamps BUT after the conversion there will be only two T-8 lamps...... or do I have that wrong ?
That's the way I'm reading it.
 
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Old 04-26-13, 06:46 AM
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I understand that before the conversion there are/were three lamps BUT after the conversion there will be only two T-8 lamps......
Correct.

I also see that T8 25-watt bulbs are available, producing around 2500 rather than 3000 lumens. Those might mitigate the problem, assuming the new bulbs are higher wattage.
 
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Old 05-01-13, 08:14 PM
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The new bulbs are GE F32T8 5000K, 25-watt. Is there a lower wattage 4' T8 available? Otherwise maybe trying 3000K might help?
 
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Old 05-01-13, 09:25 PM
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How would changing to a lower-output lamp help?
 
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Old 05-02-13, 04:43 AM
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The figures with a K behind them indicate the color temperature of the lamp. Some temperatures tend to be yellowish, some bluish etc.

https://www.google.com/search?q=bulb...w=1174&bih=715
 
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Old 05-02-13, 01:48 PM
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The figures with a K behind them indicate the color temperature of the lamp. Some temperatures tend to be yellowish, some bluish etc.
I know that. I guess my choice of the phrase "lower-output" wasn't as clear as I would have liked it to be.

What I was wondering is how changing to lamps that draw less power would improve the light levels. IMX, the lower the wattage the lower the lumens, within the same technology. Trading off lumens for an improved CRI, which is what you're likely to get by going up in [SUP]o[/SUP]K, might not turn out to be such a great deal in practice, I'm guessing.

Aeg, as far as degrees Kelvin go, why stop at 3000? I installed 6' of two-tube T8 fixtures in our laundry room many years ago and lamped them with 6500K, IIRC. Highest I could get, for sure. There are times you want to reach for your sunglasses before going in there.

If you don't see any spots or stains on the clothing under those lamps, you won't see ir anywhere outside that room, guaranteed,

The 12 feet of lamps pull 120W total when they're on. No big deal on that.
 
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Old 05-02-13, 02:22 PM
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The problem sounds like the new lamps are putting out too many lumens and the OP is looking for a way to reduce the lighting levels. In post #10 I took it that they thought they would get less light out of the 3000K vs the 5000K.
 
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Old 05-02-13, 03:18 PM
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What I was wondering is how changing to lamps that draw less power would improve the light levels. IMX, the lower the wattage the lower the lumens, within the same technology. Trading off lumens for an improved CRI, which is what you're likely to get by going up in oK, might not turn out to be such a great deal in practice, I'm guessing.

Aeg, as far as degrees Kelvin go, why stop at 3000?
Sorry, what I should have said instead of lower wattage was lower lumen rating. These T8s are rated 25 watts, 2350 mean lumens nominal.

What I am suggesting is to change the bulbs to get less light, not more. Or at least to have humans perceive less light. To me, that means lower wattage, lower lumens, or a color that seems warmer to the human eye.

(Below here is just calculations I went through to compare new vs. old.)

The old fixtures were operated with only the center bulb lit most of the time, because that gave enough light. So the issue with the new lights is that in order to get some light out of every fixture, every bulb of every fixture must be lit. (In other words, to get similarly uniform lighting, the new setup actually uses more electricity, although that's too bright.)

With the old T12 fixtures, 34,320 lumens distributed pretty uniformly, did the job.
Now the options are:
18,800 lumens, not enough.
37,600 lumens, a good amount but not well-distributed.
56,400 lumens, well-distributed but too bright.

Old T12s, 36 total bulbs (12 fixtures * 3 bulbs per fixture)
Old T12s, 12 bulbs lit under normal circumstances
Switch options: 12 bulbs lit, 24 bulbs lit, or 36 bulbs lit.
Fixture options: 1/3, 2/3 or 3/3 of each fixture lit

T12, 4100K, 40-watt bulb (Not sure of exact bulb):
Each bulb: 2860 lumens
1/3 of each fixture lit = 12 bulbs = 34,320 lumens
2/3 of each fixture lit = 24 bulbs = 68,640 lumens
3/3, all fixtures, all bulbs lit = 36 bulbs = 102,960 lumens

New T8s, 24 bulbs total (12 fixtures * 2 bulbs per fixture)
Switch options: 12 bulbs lit or 24 bulbs lit
Fixture options: Eight fixtures (Rows 1 & 3) lit, Four fixtures (Row 2) lit, or all twelve fixtures lit.

T8 lumen counts:
Each bulb: 2350 lumens
Each troffer: 2350 lumens * 2 bulbs = 4700
Four fixtures: 18,800 lumens
Eight fixtures: 37,600 lumens
Twelve fixtures: 56,400 lumens
 
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Old 05-02-13, 04:12 PM
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One option might be to change how many and the distribution of lights and how they are switched, ie better balance.
 
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Old 05-03-13, 04:07 PM
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In other words, to get similarly uniform lighting, the new setup actually uses more electricity, although that's too bright.
I wouldn't bet on it. If your new fixtures use electronic ballasts, they should produce more lumens per watt than the old setup did.

Sorry, I spaced out on why you might want to reduce the lumens earlier.
 
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Old 06-08-13, 06:44 AM
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Checked out the 3000K option. The Ecolux 25W 3000K (GE 72128) is priced high. It would be worth trying but for example Grainger (2ETR6) only sells them by the 36-tube carton. I can't even find a competing 25W 3000K 4' bulb. Is there one?

Other remaining easy option, as previously mentioned, would be to remove one bulb from each fixture. I suppose then the remaining bulb could be switched to a 32W 2700 or 3000K, which is a bit cheaper than the 25W Ecolux.

Do these bulbs really cost that much more to produce, or does GE simply have a corner on the "meets new minimum efficiency standard, effective July 14, 2012" market?
 
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Old 06-08-13, 10:16 AM
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Do these bulbs really cost that much more to produce, or does GE simply have a corner on the "meets new minimum efficiency standard, effective July 14, 2012" market?
No, there are others. Here's one example: 25W 4 Foot Energy Saving Rapid Start 3000K 83+ CRI T-8 Medium Bi-pin.
 
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