5 KVA single phase transformer bonding

[Purr24]

I am installing a 5KVA transformer 480v primary and 240/120v secondary. I understand X2 & X3 of the secondary together is your neutral connection is this also where the grounding terminates for proper bonding?

 

[infinity]

Yes, this is a little larger transformer without a neutral but a similar configuration.

 

[kwired]

You can do the bonding at the first disconnecting means, but will still be in that same conductor that lands on X2-X3, plus would still need bonding jumper or qualifying metal raceway back to transformer to bond transformer frame.

 

[tom baker]

And where the bonding is done, is where the GEC lands.
Bond at xfmr...4 wires from first disconnect
Bond at first disconnect...3 wires to transformer. Neutral size is larger of egc or unbalanced current.
For small xfmrs, with wire leads I found it easier to bond in disconnect.

 

[don_resqcapt19]

The picture shows flexible conduit so a supply side bonding jumper of the wire type is needed between the transformer and the first disconnect no matter where the system bonding jumper is installed.

 

[infinity]

The picture shows flexible conduit so a supply side bonding jumper of the wire type is needed between the transformer and the first disconnect no matter where the system bonding jumper is installed.

I agree.

 

[kwired]

And where the bonding is done, is where the GEC lands.
Bond at xfmr...4 wires from first disconnect
Bond at first disconnect...3 wires to transformer. Neutral size is larger of egc or unbalanced current.
For small xfmrs, with wire leads I found it easier to bond in disconnect.

Still need to bond to the transformer case with a jumper returning from the first disconnect - unless you have a raceway that is suitable for accomplishing that bond.

 

[Purr24]

X2-X3 connect to secondary neutral and bonded to ground lug with both primary and secondary grounds and transformer frame to steel beam?

 

[jusme123]

Yes, this is a little larger transformer without a neutral but a similar configuration.

View attachment 2552163

Primary conductors are not supposed to be brought into transformer in that rear location, on all/most transformers it’s actually a code violation.

 

[infinity]

Primary conductors are not supposed to be brought into transformer in that rear location, on all/most transformers it’s actually a code violation.

I would agree with you if the transformer were so labeled but this one had no such labeling. Some transformers have similar labels about not entering conductors above a certain point.