For a box with four 12-2 NM cables and no clamps, what is the minimum cubic inch capacity required for the box?

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Multiple Choice

For a box with four 12-2 NM cables and no clamps, what is the minimum cubic inch capacity required for the box?

Explanation:
Box-fill calculations determine how much space a junction box must provide based on the number and size of conductors inside. For 12 AWG conductors, the NEC box-fill table uses 2.25 cubic inches of volume per conductor. With four 12-2 NM cables, you have eight insulated conductors (two per cable) that originate outside and terminate inside, plus the equipment grounding conductors from the four cables. All equipment grounding conductors together count as one conductor for fill. There are no clamps to add, since the problem states none. So the equivalent conductor count is eight plus one for all grounds, totaling nine conductors. The required volume is 9 × 2.25 = 20.25 cubic inches. Therefore, the box must be at least 20.25 in³. Among the given options, the smallest size that meets this requirement is 22.5 cubic inches. If a provided answer shows 24.75 cubic inches, that reflects a different counting convention or assumption than the standard box-fill rule.

Box-fill calculations determine how much space a junction box must provide based on the number and size of conductors inside. For 12 AWG conductors, the NEC box-fill table uses 2.25 cubic inches of volume per conductor.

With four 12-2 NM cables, you have eight insulated conductors (two per cable) that originate outside and terminate inside, plus the equipment grounding conductors from the four cables. All equipment grounding conductors together count as one conductor for fill. There are no clamps to add, since the problem states none.

So the equivalent conductor count is eight plus one for all grounds, totaling nine conductors. The required volume is 9 × 2.25 = 20.25 cubic inches. Therefore, the box must be at least 20.25 in³.

Among the given options, the smallest size that meets this requirement is 22.5 cubic inches. If a provided answer shows 24.75 cubic inches, that reflects a different counting convention or assumption than the standard box-fill rule.

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