We came across a 3phase 480v 120/208 trasformer that started making noise inside that was never there before. We loto the trans and looked inside for lose connections or something out of the normal . The circuit for this unit came from below with the conductors being open coming through the cement floor without any conduit just a 4" long nipple sitting in the hole in the floor with the wiring going into the bottom of the trans with no machancal connection to the trans. It did have a egc going to the frame, with h1 h2 h3 being primary connection.
I have no idea why the nipple was there, it did not connect to either end , maybe they though it was protecting the conductors. This trans has been in service for years.
When a transformer is feed from a MCC is the xo bonded in trans or first panel ?
The second 3 phase panel will have 5 conductors,
3 phase 1 neutral and egc. [ 75 kva ]
If there is something you can add to this as to why the raddling noise inside or about the installation we will appreciate any input.
I have no idea why the nipple was there, it did not connect to either end , maybe they though it was protecting the conductors. This trans has been in service for years.
When a transformer is feed from a MCC is the xo bonded in trans or first panel ?
The second 3 phase panel will have 5 conductors,
3 phase 1 neutral and egc. [ 75 kva ]
If there is something you can add to this as to why the raddling noise inside or about the installation we will appreciate any input.