Step down transformer.

[Mustwin351]

I have a rather unusual situation where an unusual solution may work but would like feedback.

At work we have a row of column sconces that provide up and down lighting on the columns.

10 fixtures with each having 2 39w metal halide par20 lamps.
Source voltsge is 277v

The best price for replacemnt lamps is $38 dollars a lamp. I can get replacement lamps that are 120v led versions literally free through rebates from the power company.

Best option would be to just replace the fixtures but there is no money. Running a new 120v circuit in this situation is very difficult. These lights are fed from 12X12X8 junction boxes which hold the ballasts.

What are are the possibilities of a small transformer to drop my 277 to 120 at the first j box?

These led lamps only require 7 watts each. Total load would only be 140w. I also believe I have a 250VA control transformer sitting on the shelf.

Thoughts?

 

[gar]

190201-1254 EST

Mustwin351:

If your transformer is 277 to 120 at 250 VA, and the bulbs are 120 V at total load of 140 W, then technically there should be no problem. Power factor of LEDs is quite good these days, and therefore should not overheat transformer. Inrush current is not a problem. You may find 120 runs somewhat high.

.

 

[Mustwin351]

190201-1254 EST

Mustwin351:

If your transformer is 277 to 120 at 250 VA, and the bulbs are 120 V at total load of 140 W, then technically there should be no problem. Power factor of LEDs is quite good these days, and therefore should not overheat transformer. Inrush current is not a problem. You may find 120 runs somewhat high.

.

Unfortunately they are labeled as 120v hopefully they can tolerate a higher voltage.

With this setup am I creating a new seperatly derived system that will require a ground rod? Or is this setup not even an option as I’m guessing with a small 250va transformer there is no provision to ground it? Or do I just bond the grounded conductor?

 

[petersonra]

I don't see a problem with your idea. Don't forget you will need appropriate OCPD on both the primary and secondary side of the transformer.