NEC Chapter 9: Tables and Annexes Quiz

Conduit Fill and Tables

• Chapter 9, Table 1 allows additional tables: Table 4, Table 5, Table 5A, and Table 8 for conduit fill calculations.
• Rigid metal conduit fill requirements are found in Section 344.22, which refers to Chapter 9, Table 1 for enforcement.
• Tables 11(A) and 11(B) provide information for Class 2 and Class 3 AC and DC wiring systems.
• Tables 12(A) and 12(B) inform on PLFA systems.

Annex Information

• The information in NEC Annexes is not enforceable by the Authority Having Jurisdiction (AHJ).
• Tables in Annex C should only be used when all conductors in the raceway are of the same size.

Conductor Fill Percentages

• For installing one cable assembly with five conductors, the conduit fill percentage is 53%.
• When calculating the number of 10 AWG conductors in a raceway, round up if the decimal is 0.8 or greater.
• Installing six conductors in a nipple between boxes allows no fill percentage options.

Specific Conductor Capacities and Areas

• A one-inch EMT conduit can hold 16 10 AWG THHN conductors.
• 60% of the cross-sectional area of a one-inch EMT conduit is 0.519 in².
• The cross-sectional area of a 10 AWG THHN stranded copper conductor is 0.0211 in².
• In a one-inch EMT nipple 12 inches long, 24 10 AWG THHN copper conductors can be installed.

Installation and Standards

• The minimum bending radius for a one-inch EMT conduit using a hand bender is 5.75 times the conduit diameter.
• UL standard 943 covers ground-fault circuit interrupters.
• For all conductors of the same size, Table C.4 in Annex C covers intermediate metal conduit.

Accessibility and Torque Recommendations

• According to 2010 ADA standards, for a switch above a 22-inch countertop, the maximum height is 44 inches.
• In the absence of manufacturer's torque recommendations, Annex I can be consulted for guidance.

Power Systems and Conductor Limits

• A critical operations power system has a maximum downtime of none of the above for a 0.9999 availability over a year.
• In 3/8-inch FMC with an outside fitting, the maximum number of 12 AWG THHN conductors—including grounding—is 3.
• For four conductors installed in a rigid metal raceway with sealing fittings in a Class 1, Division 1 location, the permitted conduit fill is 25%.