3.3 Commercial / Non-Dwelling Demand Factors

Commercial Loads on a Journeyman Outline

Arkansas Prov’s calculation items are not limited to houses. Expect store lighting, office receptacles, restaurant kitchen equipment, and continuous loads on feeders. The skill is the same: identify occupancy → open the correct Table 220.42(A) unit load → apply Table 220.45 demand if allowed → add other loads under their own sections → apply 125% where continuous.

Do not import dwelling-only shortcuts (two 1500 VA small-appliance circuits, laundry 1500 VA, Table 220.55 household range column) into a retail or office problem unless the stem truly describes dwelling units.

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General Lighting — Table 220.42(A) and Table 220.45

NEC 2023 bases many non-dwelling lighting calculations on Table 220.42(A), General Lighting Loads by Non-Dwelling Occupancy. That table lists unit loads in VA/ft² (or other stated units) by occupancy type — banks, offices, stores, restaurants, schools, warehouses, etc. Your exam workflow:

1. Find the occupancy in Table 220.42(A).
2. Multiply unit load × floor area (using the Code’s area rules).
3. Apply Table 220.45 demand factors for that occupancy when the table provides a demand factor row for it.

Dwelling vs non-dwelling reminder: Dwellings use 220.41 (3 VA/ft²) plus dwelling demand rows. Stores/offices use Table 220.42(A) values — which are often higher VA/ft² than 3.

Illustrative store example (verify unit load in your Code book): Suppose Table 220.42(A) lists 1.9 VA/ft² for a given store occupancy (look up the exact published value). A 5000 ft² sales area → 5000 × 1.9 = 9500 VA connected lighting load before demand. If Table 220.45 allows a demand factor for that occupancy (some occupancies are 100% of the calculated lighting load), apply only what the table prints.

Offices / banks: Many non-dwelling occupancies take 100% of the general lighting load in Table 220.45 (no 35% dwelling-style reduction). That is why commercial lighting demand often stays near the full VA/ft² product — read the table row; do not assume dwelling 35%.

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Receptacle Loads — Other Than Dwelling Units

For non-dwelling receptacles, start in 220.14 for branch-circuit load values (for example, receptacle outlets calculated at not less than 180 VA per strap/yoke where that rule applies) and use feeder/service demand provisions such as 220.47 Receptacle Loads — Other Than Dwelling Units (demand factors in Table 220.47, or Table 220.45 where that section permits) when totaling multioutlet receptacle loads for feeders. In the 2020 NEC this same rule was numbered 220.44 — use the 2023 number on an Arkansas Prov form.

Typical feeder pattern (confirm exact breakpoints in 220.47 / related text):

• Sum receptacle VA (number of receptacles × 180 VA, or other method the section allows for multioutlet assemblies).
• Apply the published demand factors to that receptacle total (commonly a first portion at 100% and a remainder at a reduced percentage — open 220.47 rather than guessing).

Worked sketch: 100 general-purpose receptacles × 180 VA = 18,000 VA. If the applicable demand rule takes the first 10 kVA at 100% and the remainder at 50% (verify in your NEC edition’s 220.47), demand = 10,000 + (8000 × 0.50) = 14,000 VA. Wrong answers often leave all 18,000 VA at 100% or illegally apply dwelling Table 220.45 35% factors to receptacles.

Multioutlet assemblies, show windows, and fixed multioutlet strips have special calculation notes in 220.14 — if the stem mentions a show window, look up the VA per linear foot rule instead of counting receptacles.

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Kitchen Equipment — Other Than Dwelling Unit(s) (220.56)

Commercial cooking and kitchen equipment is not Table 220.55 household ranging. Use 220.56 and Table 220.56:

• For three or more appliances fastened in place and used for cooking, food prep, or similar kitchen loads in other-than-dwelling occupancies, Table 220.56 demand factors may apply to the total connected load.
• Demand factors in Table 220.56 decrease as the number of units increases (look up 3 units vs 6 vs 10+).

Example: Six kitchen appliances, connected total 48 kW. If Table 220.56 lists 65% for 6 units (confirm in table), demand = 48 × 0.65 = 31.2 kW. If only two appliances are present, you generally cannot take Table 220.56 demand — use the section’s rules for fewer than three (typically 100% of nameplate unless another section applies).

Restaurant questions may also reference 220.88 optional methods for new restaurants — if the stem cites 220.88, open Part IV; otherwise stay with 220.56 + lighting/receptacle rules.

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Continuous Loads and the 125% Factor

A continuous load is one where the maximum current is expected to continue for 3 hours or more. Lighting in many commercial occupancies is treated as continuous. For branch-circuit conductors, feeders, and services, related rules in 210.19(A), 215.2, and 230.42 generally require sizing to not less than 125% of the continuous load plus 100% of the noncontinuous load (with listed exceptions).

Exam assembly pattern:

1. Calculate continuous VA (often lighting).
2. Calculate noncontinuous VA (some receptacles, certain equipment).
3. Feeder VA for sizing ≈ 1.25 × continuous + 1.00 × noncontinuous.
4. Convert to amperes; select conductors/OCPD per Articles 210/215/230/240 and ampacity rules.

Example: Continuous lighting demand 20,000 VA + noncontinuous receptacle demand 8,000 VA on a 208Y/120 V feeder. Sizing load = 1.25 × 20,000 + 8,000 = 33,000 VA. Amperes for a three-phase feeder: I = 33000 ÷ (208 × 1.732) ≈ 91.6 A — then apply conductor ampacity and OCPD selection (often a follow-up).

Do not multiply already-demanded loads by 125% and also apply an illegal second demand factor. Apply demand factors first as Article 220 directs, then apply continuous-load multipliers for conductor/OCPD sizing when the question asks for that.

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Other Commercial Adders You Should Tab

Build commercial feeders as a checklist sum, not a single blended percentage.

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Full Commercial Mini-Calc (Exam Style)

Occupancy: small retail, 4000 ft². Assume Table 220.42(A) unit lighting load 1.9 VA/ft² (verify), lighting continuous, Table 220.45 demand 100% for this occupancy. Receptacles: 40 × 180 VA = 7200 VA; apply 220.47 demand as 100% of first 10 kVA + 50% of remainder → here all 7200 at 100% = 7200 VA noncontinuous for this sketch. One 3-phase motor with calculated load contribution 3000 VA; add 25% of largest motor = 750 VA.

• Lighting connected/demand = 4000 × 1.9 = 7600 VA (continuous)
• Receptacles demand = 7200 VA (treat as noncontinuous in this sketch)
• Motor + 25% = 3000 + 750 = 3750 VA
• Conductor sizing VA ≈ 1.25 × 7600 + 7200 + 3750 = 9500 + 7200 + 3750 = 20,450 VA

Prov may ask only for the lighting VA, only for whether 125% applies, or only for the receptacle demand step. Calculate the asked quantity; do not volunteer extra arithmetic that invites rounding traps.

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Timed Lookup Order for Commercial Items

1. Occupancy → Table 220.42(A)
2. Lighting demand → Table 220.45
3. Receptacles → 220.14 + 220.47
4. Kitchen → 220.56 / Table 220.56
5. Continuous? → 125% on the continuous portion for sizing questions
6. Motors / HVAC / neutrals → dedicated sections

If a distractor uses 3 VA/ft² on a store, it confused 220.41 dwelling rules with commercial unit loads.