TL;DR
Learn box fill calculations, enclosure selection, and fitting requirements. Proper box and enclosure installation ensures safety and code compliance.
Free Box Fill Calculations (Art. 314) Practice Questions
Journeyman Electrician License Exam · Electrical Theory & Trade Math
This module covers Box Fill Calculations (Art. 314) as part of the Electrical Theory & Trade Math section, testing your understanding of core concepts and their practical application.
| Exam | Journeyman Electrician License Exam |
| Pass Rate | 55% |
| Duration | 240 minutes |
| Module | Box Fill Calculations (Art. 314) |
Why Box Fill Calculations (Art. 314) matters
Box Fill Calculations (Art. 314) is one of the most tested areas because medication errors are among the most preventable causes of patient harm.
Sample Practice Questions (5)
1. A 4-inch square × 1-1/2 inch deep metal box (21.0 cu in) contains internal cable clamps and the following: 6 current-carrying 12 AWG conductors, 2 equipment grounding conductors (12 AWG), and one duplex receptacle. Is this box large enough?
- Yes — the fill is 20.25 cu in
- No — the fill is 22.50 cu in
- Yes — the fill is 18.00 cu in
- No — the fill is 24.75 cu in
2. A 4" x 2-1/8" deep square metal box (30.3 cu. in. per Table 314.16(A)) contains only 14 AWG conductors (2.0 cu. in. per conductor volume). Assuming no devices, clamps, or EGCs, what is the maximum number of 14 AWG conductors permitted?
- 15
- 12
- 16
- 10
3. A device box contains: 4 x 12 AWG conductors, 2 x 12 AWG equipment grounding conductors, and 1 single-gang device (yoke). Per NEC 314.16, how many total conductor-volume equivalents must be counted? (12 AWG = 2.25 cu. in. each)
- 7
- 8
- 6
- 9
Want more practice like this?
Start practicing free →4. Per NEC 314.16(B)(2), one or more internal cable clamps in a box count as how many conductor volumes total?
- 1 for each clamp
- 1 single volume for all clamps combined
- 2 for each clamp
- 0 — clamps do not count
5. A box contains both 14 AWG and 12 AWG conductors: 5 current-carrying 14 AWG conductors, 2 current-carrying 12 AWG conductors, 2 EGCs (one 14 AWG, one 12 AWG), internal clamps, and one switch connected to 14 AWG wires. What is the minimum required box volume?
- 22.25 cubic inches
- 20.00 cubic inches
- 24.50 cubic inches
- 18.75 cubic inches
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