Lighting ballast

[mshields]

Came accross a situation where an illuminated sign rated for 277V was running at 120V. PM wanted to know how that could be. The sign was an LED type. I said that this was a resistive load. V=IR therefore if you run it at a lower voltage you get less power and less light. If you do the opposite you'd obviously burn out the fixture given that you'd be running higher current through the fixture that that which it is rated for.

But it got me thinking, how would this work with a ballasted fixture. Are ballast just resisters. Clearly not in the case of electronic ballast right?

So what would happen if you took a 277 rated fluorescent or HID and tried to run it at 120V. Anybody?

Thanks,

Mike

 

[beanland]

LV on Ballast

LV on Ballast

Most likely there would not be enough voltage to start either the fluorescent or HID lamp and not much would happen.

Are you sure the LED is resistor ballasted? LED are LV devices. It might use a universal power supply that converts 85-280VAC into 5VDC for the LED. Wide range power supplies are found on high end computers and electronic devices.

 

[ibew441dc]

So what would happen if you took a 277 rated fluorescent or HID and tried to run it at 120V. Anybody

I guess it depends on the ballast , some ballasts have a dual rating 120 / 277. In that case the light would still function properly.

ibew441dc

 

[rattus]

Yes and no:

Yes and no:

But it got me thinking, how would this work with a ballasted fixture. Are ballast just resisters?
Mike

The conventional ballast is basically an inductor which provides an inductive reactance which limits the current with no wasted power. However, there will be a relatively small resistance which generates heat as well as iron losses which generate more heat.

 

[qcroanoke]

There is a ballast that will work on 120-277 50 or 60 Hz
Not sure of the Mfgr. name
we use it in all our buildings now.
we ship all over the world to countries with many different voltages and frequiencies these lights were a great find for us.