National Electrical Installation Standards

Standards as High as Your Own

Tuesday, February 26, 2019


Re: CQD answer published Tuesday, February 5, 2019 - System Bonding Jumper Location

Related to Wednesday's question, can one make the ground-grounded conductor bond in the transformer or should it be done in the disconnect?

Michael Casey



Hey Michael thanks for your follow up question. The connection between the grounded circuit conductor and the equipment grounding conductor is defined as a Bonding Jumper, System in Article 100. It can be installed in the transformer, the first disconnecting means or anywhere in between but must only be done at one point as stated in 250.30(A)(1). The grounding electrode conductor connection must be made at that same point as stated in the last sentence of 250.30(A)(5). The choice is yours but make sure it is only connected at one point. Some prefer to make the connections in the transformer and others at the first disconnecting means. There are advantages and disadvantages for both locations.

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