I tried to find tkrussell's previous post when he explained 1 phase, 2 phase and 3 phase - as it relates to voltage. The lights I want to install are Cooper's XF Falcon floodlights 250w MH - they say they are 277v and are "tritap 120/277/347"
I remember something about 277v not being 240v? Is the "tritap 120" a single leg of a 3 phase system not to be confused with one leg of a two phase system? Can the ballast be rewired? Can I make it work on a 2 phase system or is than impossible or stupid or both?

Thanks again for your thoughts

OK let's start with what voltages you have available.

In your first post you stated you had 240 volt fixtures?? Now they are 277 ?

I see your fixture ballast is triple tap with 120/277/347.

No, 240 volt is not 277 volt.

120 can be gotten from one leg of a 120/240 volt 1 phase system or 1 leg of a 120/208 volt 3 phase system.

Why do you ask about 2 Phase? This is an old, obsolete, and rare system, maybe still in use in some industrial plants.

No a ballast cannot be rewired.

What exactly are you trying to do?

Sorry for the confusion. I saw these lights HD and asked (first mistake that day) what voltage they were I was told 240v so I bought them. When I asked "Ask Me" about wiring and amperage and what kind of circuit would be needed I looked closer and discovered the 277v tag. That's when I started to ask the current questions. I was using "2 phase" explanation wrong - not that I actually know the right usage. I thought 2 phase was a normal residential system - 2 legs of 120v together making 240v - I then thought 3 phase was a third hot supply from the power company used in industrial applications. Mind you 120 + 120 + 120 doesn't = 277 - So not only am I wrong, I'm confused!

If you can set me in the right direction that would be great!

The question I'm hoping to answer in the end: The lights are wired 277v but also say "tritap 120/277/347" can they be wire into a normal residential system.

Thanks Again

OK that's what I needed was a better explanation, not so much of what you want to do but your perception of phases, voltages, etc.

The light your looking at will only work at home on the 120 volt tap. Disregard the 277 and 347 as those are commercial and industrial voltages.

Just keep in mind the amperage of each fixture, and again, do not have more than 16 amps on 1- 20 amp 120 volt circuit. Each fixture will have the three "taps" which should be labeled with each voltage, and there will be one wire labeled "common". The 120 volt feed will connect to the 120 volt "tap", and the white neutral will connect to the "common".

Hope this helps.

So I opened up the light and I see the 120v tap. What is the draw back with using the 120v tap (I know it's my only option!) Is it just higher amperage draw? Will it effect the intensity of the light only running off a 120v system?
Does it make sense that the one unit only draws 2.5 amps when used with the 120v tap (it's one of the numbers on the tag after A) ( 1.4a with 277v) so on a standard 15 amp circuit I easily safe running 2 units on the same supply.
It also says it needs 150 degree supply conductors - what's the least expensive way to do that? With conduit? How do you jump from the end of the conduit/octagon box into the fixture? Some kind of flexaible cable? (they are flood style lights that can have the angle adjusted after mounting)
Thanks tkrussell I hope you received my "support" -

Yes I sure did, thank you!

Yes the current draw at 120 volt will be the highest, and if higher voltages can be used then the current draw is lower. See, this is Ohm's Law at work!

Two lights at 2.5 amps each will fit on a 15 amp circuit, and no more than 4 lights on a 120 volt circuit, so there is no more than 12 amps on a 15 amp circuit.

Is the temp in Fahrenheit or Celsius? I think it is F Deg. THHN wire should be fine, which is rated for 194 deg F.

You can use PVC conduit, or EMT conduit, and pull through THHN wire. Or MC cable or even Romex may be used. Really depends on the construction of the building, and what type of wiring method is best. A picture of the space may help me decide which method works the best.

Each light will probably need a junction box as the conduit or cable goes from light to light. Then a short piece of MC cable, or Romex cable can go from the junction box to the connection box on the light. The light surely will need to be mounted directly to the wood framing as there is no electrical junction box that can support it.

Is there a draw back to using the 120v tap. Will the performance of the light be different? The intensity? I'll see what I can do about a picture thanks again!

No, the fixture will work the same on any voltage, including the wattage. There is no savings on energy to using a different voltage. the wattage will still be 300 watts, 250 watts for the lamp plus the ballast watts.

120 volts x 2.5 amps = 300 VA ( AC Watts)