Practice: commercial lighting load
Each problem uses new numbers, so you practice the method rather than memorizing an answer.
Pick the answer: sizes and ratings come from your code book.
Worked solution
Formula
| Symbol | Meaning | Unit |
|---|---|---|
| Area | Floor area from the outside dimensions (120.5(C)) | ft² |
| Unit load | VA per ft² for the occupancy, Table 120.42(A) | VA/ft² |
Worked example
Occupancy type in Table 120.42(A): retail. The building has 15,000 ft² of floor area, measured to the outside of the walls. What is the minimum general lighting load for the feeder calculation?
- Look up the unit load for this occupancy (retail) in Table 120.42(A): 1.9 VA/ft².
- Lighting load: 15,000 ft² × 1.9 VA/ft² = 28,500 VA. Under 120.5(E), do not add 125% in the load calculation itself.
Answer: 28,500 VA
Commercial lighting load, explained
For buildings other than dwellings, the minimum general lighting load is the floor area times a unit load that depends on how the building is used. Open Table 120.42(A) (Table 220.42(A) in 2023) and find the occupancy: office 1.3 VA/ft², retail 1.9, school 1.5, warehouse 1.2 and so on. The values are the same as in 2023. Older books from before 2020 show higher values such as 3.5 VA/ft² for offices; do not use them.
The 125% factor is where 2026 differs from 2023. The 2023 table had a note saying the unit loads already included the 125% continuous-load factor. The NFPA committee record for 2026 shows that note removed and a new 120.5(E) saying load calculations do not apply 125% for continuous loads. That factor now lives in conductor and OCPD sizing (215.2(A)(1) for feeders). Sources still disagree on how to read this, so check Table 120.42(A) and 120.5(E) in your own 2026 book. If a question tells you to apply 125%, follow the question.
Show windows and signs are added on top of the general lighting. A show window counts 200 VA per linear foot, measured along its base (120.14(G)). Each required sign outlet counts at least 1,200 VA (120.14(F)). Both are usually continuous loads.
For a 3-phase feeder, divide the VA by the line-to-line voltage times 1.732 to get amperes.
How to solve it on the exam
- Find the occupancy in Table 120.42(A) and read its unit load.
- Multiply by the floor area from the outside dimensions.
- Add 200 VA per linear foot of show window and 1,200 VA per sign outlet if the question has them.
- For feeder conductor sizing of continuous loads, multiply by 1.25 (215.2(A)(1)), then convert to amperes.
Common mistakes
- Using 2 or 3 VA/ft² (dwelling values) for a commercial building.
- Using pre-2020 unit loads, such as 3.5 VA/ft² for offices.
- Mixing up where the 125% goes. The 2026 NEC removed the table note that said 125% was already included. Check your 2026 book and the question wording; never apply 125% twice.
- Forgetting the 1,200 VA sign outlet or the 200 VA per foot show window load.
- Leaving out 1.732 when converting a 3-phase load to amperes.
Exam tips
- Occupancy notes under the table matter: banks are offices, stores and barber shops are retail, clubs are restaurants.
- If two choices differ by exactly 25%, the question is testing the continuous-load factor. Read whether it asks for the load or for the feeder ampacity.
Commercial lighting load calculator
Questions people ask
What is the lighting load for an office in the 2026 NEC?
1.3 VA per square foot from Table 120.42(A). Multiply by the floor area.
Does Table 120.42(A) include the 125% continuous load factor?
The 2023 table said it did. The 2026 committee record shows that note removed, and the new 120.5(E) leaves the 125% to conductor and OCPD sizing. Check the table and 120.5(E) in your own 2026 book.
How much load is a show window?
200 VA per linear foot of show window, measured along its base (120.14(G)).
What is the minimum load for a sign outlet?
1,200 VA for each required sign outlet (120.14(F)).
Sources
- TDLR: Electrician examination information
- PSI: Texas electrician Candidate Information Bulletin
- NFPA: 2026 NEC Second Draft report, Code-Making Panel 2 (Article 120)
About the tables: The exam is open book. These problems cite the 2026 NEC section and table so you practice finding them in your own book. We never print NEC text or tables.