XO tap grounding

[David 41]

What is the proper size wire that should be used to ground the XO tap on a 30 KVA delta/wye transformer? Should this ground wire be cadwelded to the building steel, or is a mechanical lug suufficient?

 

[jumper]

I think the GEC for the xfmr is sized by T250.66 according to 250.30(A)(5).

I believe that a mechanical listed for grounding may be sufficient.

 

[augie47]

what jumper said !

Assuming the 30 kva is 208 v you possibly have a #2 secondary which would be a #8 jumper and GEC, but thats an assumption based on the #2 phase wire.

 

[infinity]

Let's start by using the proper terminology. The conductor from the XO to the building steel is a GEC (grounding electrode conductor). The jumper between the XO and the transformer case is the system bonding jumper. Since you said to the building steel then the assumption is that you're referring to the GEC. The GEC is sized based on the size of the transformer secondary conductors and as Jumper stated can be found in 250.66.

Welcome to the Forum.