Oklahoma Electrical Practice Exam

What is the largest allowable fill area for a 9-inch wide cable tray where all cables are smaller than 4/0 AWG?

1. 8.5 square inches

2. 9.5 square inches

3. 10.5 square inches

4. 11.5 square inches

The correct answer is: 10.5 square inches

In determining the largest allowable fill area for a cable tray, especially for a configuration specifically like a 9-inch wide cable tray with cables smaller than 4/0 AWG, you refer to the National Electrical Code (NEC) guidelines regarding the fill area for cable trays. According to the NEC, the maximum fill area for a cable tray is often calculated based on the width of the tray and the size of the cables being used, which in this case are all less than 4/0 AWG. The fill calculations consider the cross-sectional area of the cables and provide an allowance that typically represents a percentage of the tray's internal area. For a 9-inch wide cable tray containing cables smaller than 4/0, the largest allowable fill calculated conforms to the limitations set forth in the code, ensuring safety and compliance with both filling capacities and heat dissipation requirements. The figure of 10.5 square inches, which is indicated as the correct answer, represents the maximum area that can be filled while still maintaining the necessary standards for effective operation and safety. This number is derived from careful considerations of cable capacity and tray width to ensure that the installation is efficient while avoiding overcrowding in the tray that could lead to overheating or damage to the