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, which allows for the use as well as the enforcement of this table.
True
Tables 11(A) and 11(B) are designed as information when dealing with which 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 what condition is met?
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What percentage to use for conduit fill when installing one cable assembly with five conductors in the cable assembly?
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When the calculation results in a decimal of what value or greater, can the calculated number of 10 AWG conductors 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 according to the 2010 ADA standards?
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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, what will be the maximum down time of a system with an availability of 0.9999?
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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, what percentage of conduit fill is permitted?
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Study Notes
Conduit Fill and Tables
- Chapter 9, Table 1 allows the use of additional tables including Tables 4, 5, 5A, and 8 for conduit fill calculations.
- Rigid metal conduit fill requirements mentioned in Section 344.22 reinforce the enforcement of Chapter 9, Table 1.
Class Wiring and PLFA
- Tables 11(A) and 11(B) provide guidance for Class 2 and Class 3 AC and DC wiring systems.
- Tables 12(A) and 12(B) offer information related to PLFA (Plant Life Safety Alarm).
Information and Enforcement
- Annexes of the NEC contain non-enforceable information as indicated in 90.3.
- Annex C tables are applicable only when all conductors in the raceway are of the same size, referring back to Chapter 9, Table 1.
Conduit Fill Percentages
- For installations involving one cable assembly with five conductors, a conduit fill percentage of 53% is recommended.
- When calculating the number of conductors, any decimal result of 0.8 or greater allows rounding up to the next whole number.
Conductors in Raceways
- Installing six conductors in a nipple between boxes is constrained to 'none of the above' fill as per Chapter 9, Table 1.
- A one-inch EMT conduit can accommodate up to 16 10 AWG THHN conductors.
Cross-Sectional Areas and Bending Radii
- 60% of the cross-sectional area of a one-inch EMT conduit equals 0.519 in² (as per Chapter 9, Table 4).
- The cross-sectional area of a 10 AWG THHN stranded copper conductor is 0.0211 in² (referenced in Chapter 9, Table 5).
- A one-inch EMT conduit has a minimum bending radius of 5.75 inches according to Chapter 9, Table 2.
Ground-Fault Circuit Interrupters and Standards
- Ground-fault circuit interrupters are covered by UL standard number UL 943.
- For intermediate metal conduit where conductors are uniform in size, refer to Table C.4 in Annex C.
Accessibility Standards
- According to the 2010 ADA standards, the maximum permitted height for a switch mounted above a countertop protruding 22 inches from the wall is 44 inches.
Torque Recommendations
- In cases lacking manufacturer's torque specifications, guidance from Annex I may be utilized.
Power System Availability
- For a critical operations power system functioning 8,760 hours per year, an availability rate of 0.9999 results in maximum downtime being 'none of the above'.
FMC Conduit Capacities
- The maximum number of 12 AWG THHN conductors that can be installed in 3/8-inch FMC, with an equipment grounding conductor included, is 3 as governed by section 348.22.
Conduit Fill Percentage in Sealing Fittings
- When four conductors are installed in a rigid metal raceway with a sealing fitting in Class 1, Division 1 locations, a conduit fill percentage of 25% is allowed according to 501.15(C)(6).
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Description
This quiz focuses on the conduit fill calculations and the relevant tables from Chapter 9 of the NEC. It covers concepts like rigid metal conduit requirements, Class wiring, and PLFA systems. Test your understanding of the regulations and guidelines provided in these important tables.
