120 volt loads on 480/277v gear.

[Pierre C Belarge]

Riverstrat,
What I was alluding to in my comment, is in our industry, we should try and leave nothing to guessing. If one does not know the answer, one is then guessing.


The answers provided in this thread provide experience and good info, but....I would not move forward until you have written answers from the Engineer/manufacturer that the application of the equipment meets the actual installation.

 

[infinity]

Here's a photo of "277" volt breakers used in a 120 volt application to get the higher AIC rating:

 

[gar]

101107-1416 EST

riverstrat:

A point of logic relative to your first post.

If you knew that the actual loads were conventional 120 V devices, for example incandescent bulbs rated for 120 V, that there were no transformers inside or between the panel and the 120 loads, and no major failures of these devices, then it is illogical to believe that the panel has 480/277 within it.

Furthermore what did the outlets on these circuits look like? What voltage did you measure at the outlets?

How high can you raise the applied voltage relative to its nominal rating to an incandescent bulb before it quickly burns out, or a transformer, etc.

Probing a question from some different points of view often times provides a quick answer to the question.

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