When running a grounded service conductor in parallel conduits, how is its minimum size determined?

The minimum size of a grounded service conductor when running in parallel conduits is determined by considering both the size of the largest ungrounded conductor and the load current it must carry. This approach ensures that the grounded conductor is adequately sized to handle potential fault conditions and provides a safe path for fault current back to the source.

The grounding system's effectiveness relies heavily on its ability to conduct fault currents safely, which is why it must be correlated with the largest ungrounded conductor. If there is a fault in the system, the grounded conductor should be able to carry the same amount of current as the ungrounded conductors to ensure proper operation of protective devices like circuit breakers. Additionally, considering the load current ensures that the conductor won't be overloaded under normal operating conditions, which could lead to overheating and failure.

By taking both of these factors into account, you ensure compliance with electrical codes and standards, which are designed to promote safety and reliability in electrical installations. This comprehensive consideration is critical for maintaining the integrity and performance of the electrical system.