HOLT Electricians Practice Exam

What is the continuous current-carrying capacity of 1 square inch copper busbar mounted in an unventilated enclosure?

1. 500 amperes

2. 750 amperes

3. 1000 amperes

4. 1250 amperes

The correct answer is: 1000 amperes

The continuous current-carrying capacity of a copper busbar is influenced by various factors such as its cross-sectional area, installation conditions, and ambient temperature. For a 1 square inch copper busbar, the typical continuous current-carrying capacity is generally around 1000 amperes when mounted in an unventilated enclosure. This value is derived from recognized standards that consider the heat generated by the current flowing through the busbar. In an unventilated enclosure, the capacity can be somewhat lower due to the limited heat dissipation, but the standard for a 1 square inch copper busbar typically allows for 1000 amperes of continuous current under such conditions. This is critical for ensuring that the busbar does not overheat, which could lead to insulation failure or fire hazards. The other choices presented reflect current capacities that do not align with the standard ratings for a 1 square inch copper busbar, whether considering safety margins or thermal limits established in industry guidelines. Therefore, the most accurate answer based on common electrical engineering principles is 1000 amperes for this configuration.