Project: T193700 #3725

This project is to develop a guideline which can be followed by utilities, consultants and electrical inspection agencies to validate the grounding design for new customer high voltage substations.

Design of a new high-voltage substation is often carried out by an independent consulting company with approval of the design being the responsibility of one or both the utility and electrical inspection authority. Guidelines and rules applicable to the design can be nonexistent, uncertain or very detailed. Interpretation of those rules can be ambiguous or misapplied. Utilities may apply different rules for their own in house standard designs as compared to an independent consultant's design.

Many utilities install distribution customer high voltage loads following standardized installation designs and no review by electrical inspection authorities. Consultant designs on the other hand are scrutinized by electrical inspection authorities using their own interpretations on codes and standards.

Some utilities have published guidelines to follow which include grounding and GPR while others do not have specific guidelines leaving it to the designer to be responsible and validated with the engineers stamp. Utility guidelines may make no specific reference to a GPR limit or may have very clear definition of GPR, Step/Touch voltage limits. Still other utilities may clearly state that pole mount transformers, indoor stations, transformer vaults or 15 kV systems and below are exempt from any GPR, Step/Touch voltage limits.

This project is to develop a recommended guideline for Grounding of Customer High Voltage Installations which can adopted and used by utilities, consultants and electrical inspection authorities.