Chapter 9 of the NEC provides essential tables used for the calculation of conductor sizes, conduit fill, and other practical field applications. These tables are crucial for ensuring that electrical installations comply with safety and performance standards. Here is an overview of the key tables and their applications:

Table 1: Percent of Cross Section of Conduit and Tubing for Conductors and Cables

This table provides the allowable percentages of the cross-sectional area of conduits and tubing that can be filled with conductors and cables:

• 1 conductor: 53% fill
• 2 conductors: 31% fill
• More than 2 conductors: 40% fill

These percentages ensure there is enough space within the conduit to allow for the dissipation of heat and to avoid damage to the conductors during pulling.

Table 4: Dimensions and Percent Area of Conduit and Tubing

This table lists the dimensions and the maximum fill area for various types of conduit and tubing, including Electrical Metallic Tubing (EMT), Intermediate Metal Conduit (IMC), and Rigid Metal Conduit (RMC). It is used to determine the appropriate conduit size based on the number and size of conductors.

Table 5: Dimensions of Insulated Conductors and Fixture Wires

Lists the dimensions for various sizes of insulated conductors and fixture wires, which helps in determining the appropriate conduit fill and ensuring proper installation.

Table 8: Conductor Properties

Provides information on the properties of conductors, such as resistance, reactance, and impedance. This table is essential for designing electrical systems and ensuring they operate efficiently.

Table 9: Alternating-Current Resistance and Reactance for 600-Volt Cables, 3-Phase, 60 Hz, 75°C

Offers detailed information on the resistance and reactance of cables, which is critical for calculating voltage drop and ensuring the proper operation of electrical systems.

Table 310.15(B)(16): Allowable Ampacities of Insulated Conductors

Specifies the allowable ampacities of various types of insulated conductors in different installation conditions. This table is crucial for ensuring that conductors are not overloaded, which could lead to overheating and potential fire hazards.

These tables provide the foundational data necessary for designing and installing safe and efficient electrical systems. For more detailed information and specific applications, consulting the NEC Handbook and additional resources provided by the NFPA is highly recommended.

Sources:

• Electrical License Renewal: Chapter 9 Notes and Tables
• The NEC Wiki: Chapter 9 Tables
• SunCam: NEC Chapter 9 Tables PDF