Sizing Equipment Grounding conductor on secondary side of Transformer Tap

[minesh21]

Hi,

I have heard discrepancies in approach to size an equipment grounding conductor that is on the secondary side of a transformer tap (prior to hitting the downstream overcurrent protection device). I have heard two differing responses:

1. Size it according to 250.30(A)(3) Ground Conductor which refers you to table Table 250.66.
2. Size it according to Table 250.122

I think it would be according to #1 above.

Thanks.

 

[don_resqcapt19]

The code now calls that a supply side boning jumper and in the 2014 NEC it is sized per Table 250.102(C)(1). In previous codes it is sized per Table 250.66.

 

[infinity]

As Don stated the 2014 NEC cleared up this confusing section with the addition of the table in 250.102 which is the same as T250.66. Also the NEC has given some new definitions to make what we're talking about more clear. As Don also mentioned the conductor between the transformer and the first OCPD is now called a supply side bonding jumper (SSBJ) and is sized according to the derived secondary conductor size. 250.122 would only be applicable for sizing the EGC run along with the circuit feeding the transformer primary.