Do I have to bring the neutral to the disconnect?

[Andy1845c]

Is the compressor mounted on a skid with a control panel, etc? I know a lot of the compressors we work on have boards and other electronics, well beyond, "just change the motor to 480v." But, it may be an older simpler style with nothing more than maybe a control transformer and a few starters it sounds like.

Second, I'd want to verify the OCPD in the MCC wasn't a repurposed starter bucket or similar with an instantaneous only breaker feeding the transformer.

It does have a control panel, but the control transformer for that and the starters is easy to change to a 480v input.

The MCC bucket is fused.

 

[kwired]

Fair point. For some reason I have been under the impression that delta/delta transformers are cheaper, but now i am questioning that. I'll have to do some reading on their merits. I've not run across many, but I don't have the experience that some of you here do.

480 delta to 208/120 wye is one of most commonly desired configurations and more likely to be a stock item, and therefore more likely to be lower cost simply because of the volume sold, even if they have approximately same amount of copper and steel in them as some other configuration. Delta to delta might be made from about same amount of materials but often is more of a "special order" and may cost more and may also have more lead time for ordering. Mostly depends on what is commonly sold wherever you are purchasing.

 

[tom baker]

And the delta secondary is harder to ground. The secondary needs a ground connection, or ground detection.

 

[kwired]

And the delta secondary is harder to ground. The secondary needs a ground connection, or ground detection.

It is as easy to ground as anything else, what you don't have is a neutral conductor so you must ground some other conductor.