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Danl
09-19-2015, 05:02 PM
My son gave me a couple of fluorescent lamp fixtures, I figured out which wires to connect to 120 VAC and none of the lamps came on. I traced my 120 volts all the way to the ballast, and said, "What the Heck"????? 277 Volts input? Really?

The bulbs are Phillips F32T8/TL735 units, 3 of them. The fixtures appear to be usable in exterior environments. He still has about 8 of these fixtures, but I'm gonna return these to him, I guess, unless someone can show me an easy source for 277 v.a.c. here at home.

Not a big deal, they were free to me, so no loss.

Any ideas on the 277 volt input thing?

Thanks,

Dan Lhttp://home.wavecable.com/~danlinscheid/20150919_125546.jpg

Paul Alciatore
09-19-2015, 05:42 PM
I have seen 277 Volt ballasts used where there was three phase power in the building. I think even then a transformer is needed. But you can probably run smaller gauge wiring so there must be savings. Probably only used where there are a lot of lights to run.

RussZHC
09-19-2015, 05:59 PM
Yep, what Paul said ^^^,

we've got those and 347 IIRC as well, same for base board heaters, three phase coming into the building several transformers in different locations, lots of lights, mostly high pressure sodium (its a court sport building, so think big empty barn, lots of space overhead, roof peak is maybe 35 feet), savings were supposed to be a lot esp when it was originally built in the late 1970s, not sure about now. In process of getting the "club house" area in the center over to LED.

Danl
09-19-2015, 06:09 PM
I have seen 277 Volt ballasts used where there was three phase power in the building. I think even then a transformer is needed. But you can probably run smaller gauge wiring so there must be savings. Probably only used where there are a lot of lights to run.

Yep, for all I know they had a lot of these connected. They have metal connectors to allow several to be 'daisy chained'.

So I guess I would need to swap out the ballast to use it at 120 vac, correct? Or should I see what 220 vac would to to it??? :)

Thanks,

Dan

Paul Alciatore
09-19-2015, 06:21 PM
I have no experience but kinda suspect that 220 is not going to be enough. If it is just one fixture, just get a new ballast. They don't cost that much.

PStechPaul
09-19-2015, 08:48 PM
An electronic ballast may use SMPS topology where the input is first rectified and then the output is a current regulated source that provides high voltage for starting and then the proper current for the rated power. It appears that this has three separate outputs each rated about 30 watts. The input of 0.32A at 277V is 88 watts which is what would be expected at unity power factor.

If it is an electronic ballast (https://en.wikipedia.org/wiki/Electrical_ballast) with a rectified front end, it will probably work just as well on DC, something like 380 VDC with a fairly wide tolerance. You might be able to make a voltage doubler to get 320 VDC from 120 VAC and that might be enough. You might be able to tell if it's OK on DC by checking the input resistance, which should be near infinity. You might also be able to use an old switching power supply of at least 100 watts to get the 350 VDC nominal from the 120 VAC line. The switchable input type often uses a doubler on 120V input selection.

Here is a simple 120VAC-320VDC doubler circuit. It's for about 700 watts so you can use maybe 200 uF capacitors for 90W:

http://enginuitysystems.com/pix/120AC-320DC.png

lakeside53
09-19-2015, 08:53 PM
Don't muck around. If you want to use the fixtures dump the 277 volt ballast and replace it with a 120v. 277 volt is phase to "neutral" on a 480 volt system; typically used in office building etc. 120v quality ballast are $7-14 each on ebay.

KIMFAB
09-19-2015, 09:20 PM
Instead of concerning yourself with the 277 v why not look into the fluorescent tube LED lights.
They don't use ballasts and come on when it's colder. Like this:

https://www.earthled.com/collections/t8-t12-led-fluorescent-replacement-tube-lights-that-bypass-ballast-rewire

This option assumes that the fixtures are quality units and not home despot junk.

Doozer
09-19-2015, 09:50 PM
If they are high quality fixtures, like explosion proof
then it is worth it to seek new ballasts.
If they are standard tin can garbage like Home Depo
sells, pitch them in the bin.

---Doozer

lakeside53
09-19-2015, 09:58 PM
LED - That's what I'd do. As the tubes go bad or ballasts need replacement, LED all the way.

Lew Hartswick
09-20-2015, 09:15 AM
Re-277V ballasts: I had a devil of a time finding one of those. I needed one for a lamp over a lathe that only had 208 3 phase power to it with no neutral. Finally got it but none of the
"normal" local sources had them. Worked fine after I ran one down.
...lew...

lakeside53
09-20-2015, 01:19 PM
208 power is usually from 208/120. Even with no "y" connection (the neutral) all you needed was a 208/240 volt type ballast. 277 ballasts are probably more common than 120, but not at a local box store that caters to homeowners. 277 is commercial - any real electrical supply house has them.