outdoor transformer grounding

[bsh]

I normally connect the outdoor transformer neutral to the transformer ground loop and to the building ground loop and I connect the neutral to the ground bus at the service entrance equipment. Per NEC 250.24(A)(2) I also need to make this connection outdoors. Per 250.6(A) to avoid objectionable currents I MUST NOT connect the transformer neutral/transformer grounding system to the building ground loop. Question - If the service entrance raceway is metal and is connected to the transformer enclosure should the connection between the transfomer enclosure and the transfomer neutral be made?

 

[nakulak]

the main bonding jumper at an sds is at the transformer or 1st means of disconnect. installing a main bonding jumper does not mean that there will be objectionable current on the equipment grounds or grounding electrode conductors. I don't understand your question.

 

[K2500]

I normally connect the outdoor transformer neutral to the transformer ground loop and to the building ground loop and I connect the neutral to the ground bus at the service entrance equipment.

Ignoring the word loop, I say this is complient assuming no path for objectionable current.

Question - If the service entrance raceway is metal and is connected to the transformer enclosure should the connection between the transformer enclosure and the transformer neutral be made?

plese define service entrance raceway, are you talking about the secondary conductor conduit?

 

[Cold Fusion]

I normally connect the outdoor transformer neutral to the transformer ground loop and to the building ground loop and I connect the neutral to the ground bus at the service entrance equipment. Per NEC 250.24(A)(2) I also need to make this connection outdoors. Per 250.6(A) to avoid objectionable currents I MUST NOT connect the transformer neutral/transformer grounding system to the building ground loop. Question - If the service entrance raceway is metal and is connected to the transformer enclosure should the connection between the transfomer enclosure and the transfomer neutral be made?

You got it. That is what the code requires. Hard to believe code panel 5 would mandate a connection that intentionally passes neutral curent over the grounding conductors - but they do.

cf

 

[Smart $]

... Question - If the service entrance raceway is metal and is connected to the transformer enclosure should the connection between the transfomer enclosure and the transfomer neutral be made?

No, provided the raceway is bonded at both ends.

Regarding 250.24(A)(2), drive a ground rod at or near the xfmr and connect via bonding jumper to the grounded service terminal (or conductor; aka neutral). No [direct] connection between neutral and xfmr enclosure at the xfmr. The MBJ takes care of the connection, even if it is elsewhere.