14.1 Commercial Lighting and Receptacle Load

Why Non-Dwelling Load Calculations Matter

The TX Journeyman exam's Calculations part (26 questions, 110 minutes) tests your ability to compute feeder and service loads for commercial and industrial buildings. Non-dwelling load calculations follow a different path from the single-family dwelling calculations covered in Chapter 13: the occupancy types, unit loads, demand factors, and receptacle rules are all distinct. A single wrong table value can cascade through every step of a multi-part calculation question.

2023 NEC Article 220 Renumbering

Article 220 was reorganized in the 2023 NEC. Three tables you may see referenced by older study materials have moved:

The table values themselves are the delayed 2020 NEC revisions — only the section numbers changed. This chapter cites the 2023 NEC numbers throughout.

Table 220.42(A) — General Lighting Loads by Occupancy

For non-dwelling occupancies, the minimum general lighting load equals the floor area (in square feet, measured from outside dimensions per 220.11(C)) multiplied by the unit load from Table 220.42(A).

Critical note: The table note states that the 125% continuous load factor is already included in these unit values. Do not apply an additional 125% multiplier to the general lighting load when using Table 220.42(A). This is a frequent exam trap for students who learned the pre-2020 table values (which did not include the 125% factor).

Footnotes classify unlisted occupancies: banks are office-type; barber shops and beauty parlors are retail; clubs are restaurant occupancies; commercial garages are parking garage occupancies; armories and auditoriums are gymnasium-type.

Receptacle and Outlet Loads — 220.14(A), (B), (H), and (I)

220.14(A) — Specific Loads

Lighting and receptacle outlets for specific loads (other than show windows) are calculated at not less than the computed load for those outlets. If a receptacle supplies a specific appliance, use the nameplate rating.

220.14(B) — Show Windows

Show window lighting is calculated at 200 VA per linear foot of show window, or at 125% of the connected track lighting load. This is a separate calculation from the Table 220.42(A) general lighting unit load — do not combine them.

220.14(I) — Receptacle Outlets (Non-Dwelling)

For other than dwelling units, each receptacle outlet is calculated at not less than 180 VA per yoke (strap). A standard duplex receptacle on one strap counts as 180 VA total — not 360 VA. A piece of equipment with four or more receptacles on a single strap is calculated at 90 VA per receptacle (e.g., a quad = 4 × 90 = 360 VA).

220.14(H) — Fixed Multioutlet Assemblies

In other than dwelling units and hotel/motel guest rooms, fixed multioutlet assemblies are calculated by length, not by receptacle count:

The key exam distinction: a workshop with hand tools plugging in intermittently uses the 5 ft rule; an assembly line where stations run continuously uses the 1 ft rule.

Table 220.45 — Lighting Load Demand Factors (Non-Dwelling Rows)

After computing the general lighting load from Table 220.42(A), demand factors from Table 220.45 may reduce it for feeder and service sizing only (not for branch-circuit count):

Key exam point: Offices, retail stores, restaurants, schools, churches, and garages all fall under All others at 100% — no demand factor reduction applies. A common error is mistakenly applying the hotel or warehouse brackets to an office or retail building.

Footnote: These demand factors do not apply to areas in hospitals, hotels, or motels where all lighting is likely to be energized simultaneously (operating rooms, ballrooms, dining rooms) — those areas are calculated at 100%.

220.14(K) — Banks and Office Buildings

Banks and office buildings get a rule of their own, and it is the single most-missed step in a commercial calculation. In those two occupancies the receptacle load is the larger of:

1. The load from 220.14(I) (180 VA per strap) after applying the Table 220.47 demand factors, or
2. 1 VA per square foot of floor area.

You compute both and carry the bigger number forward — you never add them. In a sparsely populated office the 1 VA/ft² floor wins; in a densely populated call center the strap count wins. Nothing equivalent exists for retail, restaurants, or schools, where 220.14(I) alone governs.

Table 220.47 — Receptacle Load Demand Factors

Receptacle loads calculated under 220.14(H) and (I) may be reduced for feeder and service sizing:

If the total receptacle load is 10,000 VA or less, no reduction applies. This demand factor is separate from the lighting demand factors in Table 220.45 — apply them independently to their respective load components.

Worked Example: 5,000 sq ft Office Building

Given: A 5,000 sq ft office building with 60 receptacle outlets, each on one strap/yoke.

Step 1 — General Lighting Load (Table 220.42(A))

• Unit load for office = 1.3 VA/ft²
• 5,000 ft² × 1.3 VA/ft² = 6,500 VA
• The 125% continuous factor is already included — do not apply again.

Step 2 — Receptacle Load (220.14(I))

• 60 straps × 180 VA/strap = 10,800 VA

Step 3 — Apply Table 220.45 Demand Factor to Lighting

• Office = "All others" → 100%
• 6,500 VA × 100% = 6,500 VA

Step 4 — Apply Table 220.47 Demand Factor to Receptacles

• First 10,000 VA × 100% = 10,000 VA
• Remaining 800 VA × 50% = 400 VA
• Receptacle demand = 10,400 VA

Step 5 — Apply the 220.14(K) Comparison

Because this is an office building, 220.14(K) requires a comparison before the receptacle number is final:

The larger of the two governs, so the receptacle load stays at 10,400 VA. Had this office contained only 20 receptacles, (K)(1) would have produced 3,600 VA and the 5,000 VA floor from (K)(2) would have taken over — which is exactly the case the capstone in Section 14.4 walks through.

Step 6 — Total Computed Load

• 6,500 + 10,400 = 16,900 VA

If this building were served by a 240 V single-phase feeder:

• I = 16,900 VA ÷ 240 V = 70.4 A

This example demonstrates the two independent demand factor tables plus the office-building floor: Table 220.45 applies to general lighting, Table 220.47 applies to receptacles, and 220.14(K) then checks the receptacle result against 1 VA per square foot. For an office building, the lighting demand factor is 100% (All others), while the receptacle demand factor reduces the load only above 10 kVA.