EG for Facility Transformer

[faresos]

Hello Everyone,

I have a situation where the customer owns the medium voltage equipment (switchgear) and feeds a number of transformers (12.47KV-480Y/277V). I know we don't pull EG for utility transformers to the main switchboard (first disconnecting means). Since this transformer is not owned by the utility, is EG still required to be pulled in addition to the phase and neutral conductors? If not, can the grounded conductor (neutral) be sized based on table 250.66?

Thanks,

 

[petersonra]

I think this might be a SSBJ instead of an EGC.

 

[texie]

Hello Everyone,

I have a situation where the customer owns the medium voltage equipment (switchgear) and feeds a number of transformers (12.47KV-480Y/277V). I know we don't pull EG for utility transformers to the main switchboard (first disconnecting means). Since this transformer is not owned by the utility, is EG still required to be pulled in addition to the phase and neutral conductors? If not, can the grounded conductor (neutral) be sized based on table 250.66?

Thanks,

As mentioned, this would be a supply side bonding jumper if it is needed. Terms are important when it comes to code but especially grounding and bonding. 250.30 (A)(1) Exception #2 may apply if the transformer is outside. Also see all of 250.30(A). Also, a SSBJ jumper will be sized per Table 250.102 (C)(1) as detailed in 250.30(A). The grounded conductor must also be sized per Table 250.102(C)(1) or the minimum calculated load, whichever is greater.

 

[electrofelon]

The neutral may be able to be used as the bonding conductor (like a service) if this qualifies as and is setup as an MGN system.

 

[don_resqcapt19]

The neutral may be able to be used as the bonding conductor (like a service) if this qualifies as and is setup as an MGN system.

The rule for multi-grounded neutrals is in Part X of Article 250 and only applies to systems over 1000 volts. The system in question here is a 480 volt system.

It is my opinion that this system will need a supply side bonding jumper between the transformer and the first disconnecting means on the secondary of the transformer.

 

[faresos]

Reading more into it, it appears I still need to provide supply side bonding jumper and the neutral between the transformer secondary and the first disconnecting means.

 

[electrofelon]

The rule for multi-grounded neutrals is in Part X of Article 250 and only applies to systems over 1000 volts. The system in question here is a 480 volt system.

It is my opinion that this system will need a supply side bonding jumper between the transformer and the first disconnecting means on the secondary of the transformer.

My original interpretation was that the OP was talking about the MV distribution/transformers. Upon rereading it I agree he seems to be talking about the 480 feed from transformer secondary to switchboard, in which case yes I agree the MGN provision would not apply.