In 480V circuits, the arc current typically does not exceed what percentage of the available bolted fault current?

In 480V circuits, it is commonly acknowledged that the arc current typically does not exceed 60% of the available bolted fault current. This figure is significant because it reflects industry practices and standards in electrical safety.

The concept of arc flash is crucial in understanding this limitation. When an arcing fault occurs, the resulting current can be dangerous, and it is essential to assess the potential current that could flow during such an event. The 60% figure is based on empirical data and helps in calculating the necessary protective measures, like selecting the appropriate circuit breakers, to ensure worker safety and minimize equipment damage.

Additionally, understanding this limitation helps in the design and implementation of protective relays, fuses, and circuit breakers, ensuring that they are adequately rated to interrupt the fault current before it can escalate into a hazardous situation. This percentage provides a guideline for engineers and electricians when performing risk assessments and setting up necessary safety equipment in industrial settings.