# 277v. on 240v. circuit ???



## K2 (Jul 8, 2005)

A maintenance guy out at the air base told me he took home some fluorescent fixtures with 277 ballast in them, hooked them up to 240 volt in his shop and has been running them for a couple of years like that. I thought he was fibbing. I asked the EE and the Master electrician I work for and they said it would not work, 1 hot,2 hots bla bla bla. 

So to confirm I hooked up a 277 mag ballast fluorescent at my shop to 240 and to my suprise it worked.. Ran it for about an hour. Looked good on the light meter. 

Is there a simple explanation ?? Just looking at the theory side of it and not that lights should ever be hooked up this way. 

Havn't tried a 277 e ballast this way yet.


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## mdshunk (Mar 13, 2005)

Eh, it will work. No doubt about it. It's just not good for the ballast. It will have a shortened life. Most ballasts can tolerate + or - 10%, so that's 27 volts either way with no special problems. 250 volts would be the lower limit, but at 240, you're a little bit below the lower limit. Other than the fact that you're being hard on an otherwise free ballast, who cares. 

By the way, the electrician who way hem-hawing around about "one hot-two hots" is an idiot, and a shame to our trade. True, 277 volts is the phase to neutral voltage if a 480 wye 3-phase system, but that does't matter. It's just coincidence. It doesn't matter, since it's single phase. Voltage is voltage, no matter how it's derived. 240 is pretty close to 277, so that's why it works. Do this with a cheap Chinese ballast, and you might not have quite as good of results.


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## K2 (Jul 8, 2005)

Thanks MD. I was thinking "voltage is voltage " but I'm still not getting the wye stuff.

I won't tell my bosses what you think of them. They are actually pretty smart on a bunch of things.


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## K2 (Jul 8, 2005)

It turns out I've been working for a couple of week with a new ballast. GE Ultramax. The label says "Wide Range 120-277" The spec sheet says it will run on any voltage between 108v and 305v. So I thinking it will work for 208v and 240v but I havn't seen anything that specific stated yet.

This instant start, (parallel wired), ballast has an easier bulb start and is recomended for use with occupancy sensors.


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## mdshunk (Mar 13, 2005)

Yeah, I've used the Advance "Intellivolt" quite a bit, too. Basically the same thing.


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## K2 (Jul 8, 2005)

mdshunk said:


> Yeah, I've used the Advance "Intellivolt" quite a bit, too. Basically the same thing.


So do you think running these at 240 in a shop/garage might be ok?? They mention 120 and 277 in their literature but never actually mention 208,240.


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