Questions and Answers
The use of Chapter 9, Table 1 for conduit fill allows the use of which additional tables in the notes to Table 1?
Tables 4, 5, 5A, and 8
Fill requirements for rigid metal conduit are addressed in Section 344.22 and refer the user to Chapter 9, Table 1.
True
Tables 11(A) and 11(B) are designed as information when dealing with what systems?
Class 2 and Class 3 AC and DC wiring
Tables 12(A) and 12(B) are designed as information when dealing with what?
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The information in the Annexes of the NEC is enforceable by the AHJ.
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The tables in Annex C are to be used only when the conductors in the raceway are all what?
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The percentage to use for conduit fill when installing one cable assembly with five conductors is what?
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When calculating the number of 10 AWG conductors that may be installed in a raceway, what decimal or greater should be rounded up?
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When installing six conductors in a nipple between boxes, what fill shall be permitted to be used?
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How many 10 AWG THHN conductors may be installed in a one-inch EMT conduit?
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What is 60% of the cross-sectional area of a one-inch EMT conduit?
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What is the cross-sectional area of a 10 AWG THHN stranded copper conductor?
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How many 10 AWG THHN copper conductors may be installed in a one-inch EMT nipple 12 inches long?
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What is the minimum bending radius of one-inch EMT conduit using a hand bender?
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What UL standard number covers ground-fault circuit interrupters?
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Where all of the conductors are the same size, which table in Annex C covers intermediate metal conduit?
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Using the forward reach requirements, what is the maximum height allowed for a switch installed on the wall above a countertop that protrudes 22 inches from the wall?
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In the absence of manufacturer's torque recommendations, what may be used?
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For a critical operations power system using 8,760 hours for a typical year, a system with an availability of 0.9999 will have a maximum downtime of what?
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What is the maximum number of 12 AWG THHN conductors that can be installed in 3/8-inch FMC, where the fitting is on the outside of the conduit?
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When installing four conductors in a rigid metal raceway with a sealing fitting in a Class 1, Division 1 location, what percentage of conduit fill is permitted?
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Study Notes
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%.
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Description
Test your knowledge of Chapter 9 of the NEC, focusing on the tables and informative annexes crucial for understanding conduit fill requirements. This quiz covers key references within the chapter, including various tables and sections that enhance your understanding of the code.
