NEC 250.30(A)(1) Exception No. 2

[wrking]

If you have a non-utility owned pad mounted outdoor transformer does 250.30(A)(1) Exception No. 2 and 250.30(A)(2) Exception allow you to treat the bonding connections with the transformer and the first disconnect as you would a utility owned transformer? i.e. no bonding jumper is allowed.

The wording "...a system bonding jumper at both the source and the first disconnecting means shall be permitting if doing so does not establish a parallel path for the ground conductor." Does "at both" simply mean between?

Thanks,

WK

 

[GoldDigger]

If you have a non-utility owned pad mounted outdoor transformer does 250.30(A)(1) Exception No. 2 and 250.30(A)(2) Exception allow you to treat the bonding connections with the transformer and the first disconnect as you would a utility owned transformer? i.e. no bonding jumper is allowed.

The wording "...a system bonding jumper at both the source and the first disconnecting means shall be permitting if doing so does not establish a parallel path for the ground conductor." Does "at both" simply mean between?

Thanks,

WK

No, it means exactly what it says following the rules of English grammar. It means one bonding connection at one location and one at the other.
To avoid establishing a parallel metallic path you simply do not link the disconnect and the transformer with a wire or raceway EGC.

 

[david]

If you have a non-utility owned pad mounted outdoor transformer does 250.30(A)(1) Exception No. 2 and 250.30(A)(2) Exception allow you to treat the bonding connections with the transformer and the first disconnect as you would a utility owned transformer? i.e. no bonding jumper is allowed.

The wording "...a system bonding jumper at both the source and the first disconnecting means shall be permitting if doing so does not establish a parallel path for the ground conductor." Does "at both" simply mean between?

Thanks,

WK

A system bonding jumper s always required at the source if the separately derived system source is outside. the grounded conductor of the outside transformer is required to be bonded to a grounding electrode outside

As stated in post # 2 you cannot use a system bonding jumper at the building (service rated disconnect) if you have a metallic path other than the grounded conductor between the outside source and the buildings main disconnect

The building is required a grounding electrode system what needs to be determined is what the electrode system needs bonded to

 

[LarryFine]

As stated in post # 2 you cannot use a system bonding jumper at the building (service rated disconnect) if you have a metallic path other than the grounded conductor between the outside source and the buildings main disconnect

In other words, the main disco is wired like a sub-panel.