Ballast wiring 277 vs 120 V

[Davebones]

Have a power outage scheduled for the weekend . Have some T8 lights wired to 277V right now . These are the dual rated ballast . Can we run a temporary 120V feed to these after they have been ran on 277 V ?

 

[tom baker]

See no reason why not. The ballast takes either 277 or 120 and converts it to the correct voltage.

 

[cadpoint]

I would get in the air and open a light, maybe even a few.

The exact type of ballast will determine if a new voltage can be applied. I just searched Phillips 68
page ballast pdf and there was nothing on dual rated ballasts.

Most I've ever ran into - burn into to the voltage that is first applied.
Good luck with the shout down...

 

[apjames]

yea ive heard of ballasts "locking into" whatever first voltage is applied.

 

[broadgage]

Over here we use 110 volts derived from transformers for temporary lighting on construction sites, and 230/240 volts for virtually all other lighting.

Duel voltage fixtures are available, and they work fine on either voltage, regardless as to which voltage was used first.
The ballasts are "made in USA" and work fine on 110 volts nominal, which is often 100 volts actual, and also on 230 volts.

 

[Little Bill]

Over here we use 110 volts derived from transformers for temporary lighting on construction sites, and 230/240 volts for virtually all other lighting.

Duel voltage fixtures are available, and they work fine on either voltage, regardless as to which voltage was used first.
The ballasts are "made in USA" and work fine on 110 volts nominal, which is often 100 volts actual, and also on 230 volts.

I haven't experienced one yet, but supposedly some of the "universal voltage" type ballast will lock in on the first voltage that was applied to it.

ie; If you used it on 277V, then changed to 120V, the ballast wouldn't work on the lower voltage because it conditioned its self to the 277V.

Also said to do the same if the lower voltage was applied first. Will lock in on the lower voltage and won't work on the higher voltage if changed to it.

 

[broadgage]

All the ones that I have tried work on any voltage in the range, no matter in what order these voltages are applied, I have got one that I use regulary on both 110 and on 240 volt circuits and it works fine.

This may not be true of all types of course.

 

[infinity]

We do this on just about every job. We install the permanent 277 volts lights (universal ballasts) and power them from the temporary 208Y/120 volt service @120 volts. Once the permanent 480Y/277 volt equipment is installed we swing it over.

 

[Davebones]

Thanks for the input . We did power the 277 v lights back up with 120v and they worked fine . The guy that installed these told me it was the salesman that told him once they had been powered up on a certain voltage you couldn't change it . Go figure !

 

[infinity]

The guy that installed these told me it was the salesman that told him once they had been powered up on a certain voltage you couldn't change it . Go figure !

Although they're sometimes called smart ballasts, they're not that smart.

 

[abhishekbt]

Yes, you can do so. The ballast can transfer these 277 or 120 to the correct voltage and it should not have any side effect in my experience, but you need to be sure before taking any steps as you cannot play with electricity.

 

[sparkycoog]

Glad it worked out, but I've run into situations where people "borrow" power from junction boxes for additions long after construction so I'm always paranoid and check to see if someone decided to add something else is connected to the circuit - ie. a wallpack where the boss parks his car and those ballasts use different inputs for different voltages.