Box Fill and Conduit Fill Practice Test

In a complete raceway run (not a short nipple), what maximum fill does Chapter 9, Table 1 permit for exactly 2 conductors?

• A31%
• B40%
• C53%
• D60%

Which NEC rule covers counting device yokes (straps) in box fill calculations?

• A314.16(B)(4)
• B314.16(B)(2)
• C314.28
• D300.3(B)

In conduit bending, an “offset” is MOST commonly used to:

• AMove the conduit path around an obstruction while staying on the same general run
• BMake a threaded connection to rigid conduit
• CIncrease conduit fill capacity
• DEliminate the need for a junction box

A metal box has a listed extension ring installed with a marked volume. For box fill purposes, the additional volume is:

• AAdded to the box volume, because the ring is marked with its volume
• BNever allowed to be counted toward box fill
• CCounted only if the circuit is 15A
• DSubtracted from the box volume because it reduces space

When performing conduit fill calculations, conductor sizes and areas are typically taken from which NEC table?

• AChapter 9, Table 5
• BChapter 9, Table 1
• CTable 310.16
• DTable 250.122

A box contains 3 insulated 10 AWG conductors entering from outside, two 10 AWG equipment grounding conductors entering, and one internal cable clamp. No devices. What is the required box volume?

• A12.5 in³
• B10.0 in³
• C15.0 in³
• D7.5 in³

In a Chapter 9 conduit fill problem, what determines which Table 1 fill percentage applies?

• AThe number of conductors and cables in the raceway
• BThe breaker size from Table 310.16
• CThe grounding electrode conductor size
• DThe circuit voltage

NEC box fill rules are primarily intended to prevent:

• AOvercrowding that can damage conductors and create overheating or workmanship issues
• BVoltage drop caused by long conductor runs
• CShort circuits caused only by incorrect breaker sizing
• DGround-faults caused by missing bonding jumpers

Which statement BEST reflects how conduit fill is determined in NEC Chapter 9?

• ABy comparing total conductor area (Table 5) to allowable raceway fill area using Table 1 percentages
• BBy using the breaker size and multiplying by 1.25
• CBy using the equipment grounding conductor table
• DBy using burial depth requirements

For box fill calculations, the volume allowance (in³) for each counted conductor is determined by:

• AThat conductor’s AWG size, using Table 314.16(B) volume allowances
• BThe breaker size protecting the circuit
• CThe number of cables entering the box only
• DThe length of conductors in the box

A complete conduit run (not a short nipple) contains 6 conductors. Under Chapter 9, Table 1, the maximum fill is:

• A40%
• B31%
• C53%
• D60%

A box contains 5 insulated 12 AWG conductors entering from outside, three 12 AWG equipment grounding conductors entering, and one duplex receptacle on a single yoke connected to 12 AWG conductors. No internal clamp. What is the required box volume?

• A18.0 in³
• B15.75 in³
• C20.25 in³
• D13.50 in³

Dimensions of compact copper and aluminum building wire for conduit fill calculations are found in:

• AChapter 9, Table 5A
• BChapter 9, Table 5
• CTable 310.16
• DChapter 9, Table 8

Which statement BEST describes pigtails in box fill calculations?

• APigtails that originate and terminate within the same box generally do not count as conductors for box fill
• BEvery pigtail counts as one conductor volume allowance
• CPigtails count only if they are neutrals
• DPigtails count as two allowances because they are spliced

When calculating conduit fill using Chapter 9 tables, you typically compare the TOTAL area of all conductors to:

• AThe allowable fill area for the raceway size at the applicable % fill
• BThe ampacity of the conductor in Table 310.16
• CThe equipment grounding conductor size in Table 250.122
• DThe burial depth in Table 300.5