Reverse Feed Transformer
- Thread starter mannyb
- Start date
- Status
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Maybe, maybe not.
First off, a LOT of 480-208Y120 transformers have the 480 side configured as Delta, so there would be no 277 available if that's the case.
Second, if they DO have a 480/277 Wye primary on that transformer, the transformer must specifically STATE that it can be used in reverse (step-up) configuration, either on the nameplate or in manufacturer's data, and if being inspected, you should have that manufacturer's data at the ready when the AHJ shows up. Then if they do use it, they must NOT connect the XO terminal on the 208V side.
First off, a LOT of 480-208Y120 transformers have the 480 side configured as Delta, so there would be no 277 available if that's the case.
Second, if they DO have a 480/277 Wye primary on that transformer, the transformer must specifically STATE that it can be used in reverse (step-up) configuration, either on the nameplate or in manufacturer's data, and if being inspected, you should have that manufacturer's data at the ready when the AHJ shows up. Then if they do use it, they must NOT connect the XO terminal on the 208V side.
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Xfmrs are are usually delta wye. f you reverse its wye delta, you would have ungrounded delta on secondary and need GF detection
As pointed out, only allowed if xfmr is listed for reverse connection.
As pointed out, only allowed if xfmr is listed for reverse connection.
Cant I just ground B phase to ground vs Detection?
- Occupation
- Licensed Electrician
Yes you can. Unless the only thing you are feeding is an old motor the better option is to get a delty/wye step up transformer. Corner grounds are a rare bird for a reason.
You originally stated you wanted 277/480 on the secondary.
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