3- phase to 1-phase system.

[inforaj]

In one of the projects, the client had 480V main panel, and all lighting was using 480V. But now they want to replace the lights, and all three-phase lights are costly instead of single-phase lights. What is the best way to use a single-phase rather than a 3-phase system?

The option that I am assuming.
1. use the 3-phase to 1-phase step-down transformer, but transformer cost increased the project.
2. connect and make a three-phase breaker into 3 separate busbars, use the branch 1-phase branch circuit, and supply all lights.
3. or any other options.

 

[electrofelon]

In one of the projects, the client had 480V main panel, and all lighting was using 480V. But now they want to replace the lights, and all three-phase lights are costly instead of single-phase lights. What is the best way to use a single-phase rather than a 3-phase system?

The option that I am assuming.
1. use the 3-phase to 1-phase step-down transformer, but transformer cost increased the project.
2. connect and make a three-phase breaker into 3 separate busbars, use the branch 1-phase branch circuit, and supply all lights.
3. or any other options.

Three phase lights????

 

[drcampbell]

Maybe, back in the olden days of magnetic ballasts, there were three-lamp (or six-lamp) fluorescent fixtures with three ballasts to cut down on visible 60-Hz flicker? I've never seen one but can envision a premium line of fixtures being sold on the basis of greater comfort. Or maybe for shops with rotating machinery, to improve safety by minimizing the stroboscope effect?

 

[winnie]

The first point to clarify is if you have some variety of pure 480V system (eg. 480V corner grounded delta, 480V high leg delta, 480V ungrounded, etc) or if you have the rather more common 480/277V grounded wye system.

If you have a 480/277V grounded wye system, then the simplest approach is to simply distribute ordinary 277V single phase light fixtures across the 3 phases to provide a balanced 3 phase load.

-Jon

 

[hillbilly1]

Or single phase 480……connect fixtures in a balanced configuration. I will assume the new fixtures are LED, and if it’s a real old system, the breakers may be 30 amp, and need to be changed to 15 or 20, or otherwise individually fusing the fixtures.

 

[inforaj]

The first point to clarify is if you have some variety of pure 480V system (eg. 480V corner grounded delta, 480V high leg delta, 480V ungrounded, etc) or if you have the rather more common 480/277V grounded wye system.

If you have a 480/277V grounded wye system, then the simplest approach is to simply distribute ordinary 277V single phase light fixtures across the 3 phases to provide a balanced 3 phase load.

-Jon

480 V, and 4 wire(wye) system.

 

[augie47]

Since you have a 4 wire system you should not need a transformer.
The plan now is to see how you can obtain a neutral at the present fixtures (adding a neutral back to the neutral available spot, change a phase conductor to a neutral, etc)
Be wise to compare the current requirements on the new fixtures to the old ones so you can plan accordingly.

 

[LarryFine]

480 V, and 4 wire(wye) system.

In that case, this:

If you have a 480/277V grounded wye system, then the simplest approach is to simply distribute ordinary 277V single phase light fixtures across the 3 phases to provide a balanced 3 phase load.

 

[Russs57]

All things equal, I'd rather have single phase 480 than 277 for outdoor/parking lot lighting. All depends on developed wiring length and the lighting load.

If it is interior lighting I'd be more inclined to use 277 unless it was something like industrial/warehouse.

 

[hillbilly1]

Actually the majority of retail big box stores are now going to 480 single phase on interior lighting. Manufacturers are now making 480 volt drivers for LED fixtures. Before, small transformers or multitap auto transformers for fluorescent or hid fixtures were used to drop to a usable voltage for the LED drivers. The OP should be able to get 480 volt LED fixtures relatively easy. No wiring changes needed.

 

[Terminator5047]

Just wait till they get a LSIG main let the fun begin

 

[JoeStillman]

It may have been 277V lights on a 480V multi-wire branch circuit, therefore, 3-pole breakers feeding lights. See 310.15(B).

 

[tortuga]

Actually the majority of retail big box stores are now going to 480 single phase on interior lighting. Manufacturers are now making 480 volt drivers for LED fixtures. Before, small transformers or multitap auto transformers for fluorescent or hid fixtures were used to drop to a usable voltage for the LED drivers. The OP should be able to get 480 volt LED fixtures relatively easy. No wiring changes needed.

That's interesting I have not seen this so you pull a 3 wire 480V circuit no noodle, and connect lights single phase L-L balancing the legs ?

 

[hillbilly1]

That's interesting I have not seen this so you pull a 3 wire 480V circuit no noodle, and connect lights single phase L-L balancing the legs ?

Yep. Pretty common in the states now.