Multi-Tap lights

[toddro1971]

I was tasked to install four low-bay light fixtures in a manufacturing plant. The 120 volt circuits originating from a 240/120 volt panel were already there, lights never got put up. So I ordered 4 multi-tap low bay fixtures with taps of 120/208/240/277 volts. Now the plans have been changed and the owner wants to run the lights on 240 volt circuits instead of 120. Correct me if I'm wrong, but will not this require a new circuit. I mean every one of these lights i have ever installed you have one hot wire (TAP) which is one of these voltages and then a common. I can not get 240 volts off a single wire out of a single phase 120/240 volt panel right? I can get two hot legs and have 240 or 120 with a nuetral. How can i wire a single 240 volt tap, I can't right. My common has to go to a nuetral not another hot leg . Whether 120 to neutral or 240 or 208 or 277 to nuetral or whatever. RIGHT? These lights we ordered ain't gonna hunt right?

 

[toddro1971]

Re: Multi-Tap lights

Just to add some more info. All of the existing lights are on a 120 volt circuit. Just four of them did not get installed for whatever reason. There is another building which has 277 volt lighting which is why i ordered multi-taps. Kill two birds with one stone.

 

[iwire]

Re: Multi-Tap lights

With a multi tap ballast you always use the ballast 'common' and one of the ballast leads with the correct marked voltage.

For 240 operation the ballast 'common' will in fact go to one of the panel hot legs and the 240 volt lead will go to the other hot leg, you will not need a neutral.

However if this job is in pipe you may not remark the white to be used as a hot.

 

[toddro1971]

Re: Multi-Tap lights

Thanks, BOB Never wired high bay lights on anything other than 277 or 120. How the heck does the transformer know that "hey, ive got two hot legs here instead of a nuetral?" I mean common sense dictates that this would not work, it's not an electronic ballast. Now i'm more curious.

 

[iwire]

Re: Multi-Tap lights

The ballast does not care if it is connected to a grounded conductor or not.

The wire labeled common is just the start of the transformers winding, the 120, 208, 240, 277 taps are the other end of that winding although they are tapped at different places on that winding.

That is why you must insulate the unused leads as they will be live also.

If you where to feed the ballast with a neutral and 277 you would find that the lead marked 120 would be live at 120 volts, this is sometimes used to feed 120 volt quartz lamps used as back up to the HID lamp.