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#204352 12/01/11 09:08 PM
Joined: Apr 2002
Posts: 195
triple Offline OP
Are there any 120-277 volt ballasts that become "locked-in" (whether by design or by fault) to a certain voltage once used?

Joined: Apr 2002
Posts: 7,333
Likes: 7

Over the years, my service guys changed an awful lot of ballasts, but I can't say that I heard of any that locked into a voltage.

I know of some that went to the graveyard before their time, and some that met their demise by having 277 applied in lieu of 120!

I asked a service sparky Friday at a office bldg, he never tried to check if any would work on one voltage and not the other.

Anybody have any input??

Joined: Feb 2002
Posts: 2,233

The only multi voltage ballasts I have seen are usually multi-tapped. It has been awhile since I was out in the fields with the tools. They might have something new that I don't know about. I am heading to my supply house this afternoon and I can check in with them.

Joined: Apr 2002
Posts: 7,333
Likes: 7

There have been, and probably still are electronic ballasts for T8 lamps that are multi voltage input. I remember 120/277 with single input (hot-neutral) factory conductors, and the internal ballast components sensed the input voltage.

I also remember (with 'new' electronic ballasts) not reading the label, and putting 277 to the 120 volt only ones! No disaster, only the ominous click, not even a puff of smoke.

The OP is wondering IF say you put 277 into a ballast, could you still use it for 120, or is it 'locked' into looking for 277?

Joined: Dec 2003
Posts: 886
I have only heard it mentioned. Never saw one myself.


Joined: Sep 2011
Posts: 66
Ive taken smart volt ballasts that ran at 277 for sometime and put them in 120 volt fixtures without issues.

I see no reason why any one ballast would become locked in nor do I think it would hurt to try. As long as its within range of the label it will be fine

Joined: Apr 2002
Posts: 7,333
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Hey, thanks for the input on this. And, if noone said it to you yet....Welcome to ECN Forums!!

Jump right in anytime.

Joined: Mar 2011
Posts: 98
Years ago, remember we've been using the electronic fluorescent ballasts out here for nearly 3 decades now, the multi-volt ballasts were said to have a sacrificial 'jumper' that burned out depending on the first voltage is was connected to.

That made it unusable for any other voltage after.

That was then and today it's not the case (from what I've seen and read), but there's a LOT of sparky's out there that still go by that belief. Our own warehouse has hundreds of electronic ballasts in bins labeled as good for only one voltage, how many actually are is for someone else to determine.

Joined: Nov 2007
Posts: 763
I also recall hearing something about this issue on multi-volt ballasts back in the early 1990’s, but I never was able to confirm it myself.
I do seem to remember that some older Grasslin DT series multi-volt defrost timers I installed on walk-in freezers had what they called automatic voltage adjustment. They would work on 120/208/240. You just hooked them up and they would “burn in” at whatever supply voltage they were connected to.
They must have done away with that feature, because the last ones I saw had the little DIP switches on the board that you manually set for the required voltage.

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