6.5 Commercial Kitchens, Schools & Restaurants (2026 NEC 120.56, 120.86 & 120.88)

6.5 Commercial Kitchens, Schools & Restaurants (2026 NEC 120.56, 120.86 & 120.88)

Quick Answer: Feeder demand for commercial kitchen equipment is governed by NEC Table 120.56, which applies tiered diversity factors based on the total number of appliances: 100% for 1–2 units, 90% for 3 units, 80% for 4 units, 70% for 5 units, and 65% for 6 or more units. Crucially, Section 120.56 establishes an unyielding statutory floor: in no case shall the calculated feeder demand be less than the sum of the two largest kitchen loads. For educational facilities equipped with electric heating or cooling, NEC 120.86 provides an optional method evaluating total connected load per square foot: 100% of the first $3\text{ VA/ft}^2$, 75% of the next $17\text{ VA/ft}^2$ ($3\text{ to } 20\text{ VA/ft}^2$), and 25% of any remainder over $20\text{ VA/ft}^2$.

Certain commercial occupancy classes present concentrated, highly specialized electrical profiles. Commercial food service facilities (restaurants, institutional cafeterias, corporate dining rooms) feature heavy concentrations of high-kilowatt heating, cooking, and sanitation equipment. Conversely, academic buildings feature expansive physical footprints with variable occupancy schedules.

To prevent unnecessary oversizing, the NEC provides specialized demand schedules in the standard and optional feeder and service calculations of Article 120 (Article 120 in the 2023 and earlier editions).

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Commercial Kitchen Equipment Sizing (NEC 120.56 & Table 120.56)

Under NEC Section 120.56, the load for commercial electric cooking equipment, dishwasher booster heaters, and other kitchen equipment may be calculated with the demand factors of Table 120.56. Electricians must recognize that NEC Table 120.55 applies strictly to household cooking equipment; commercial food service equipment can never be calculated using Table 120.55.

Table 120.56 Demand Factor Schedule

Qualifying Equipment Scope

Equipment that qualifies for the Table 120.56 demand factors includes commercially rated:

• Electric deep-fat fryers
• Commercial convection and deck ovens
• Commercial griddles, broilers, and salamanders
• Commercial dishwashers and hot-water booster heaters
• Steam kettles, tilting skillets, and steam tables
• Commercial food warmers and holding cabinets
• Commercial electric ranges and cooktops

Explicit Exclusions Under NEC 120.56

Section 120.56 explicitly states that these demand factors do not apply to:

1. Electric space-heating equipment (calculated under Article 424).
2. Ventilation fans and make-up air systems (calculated under Article 430).
3. Air-conditioning and refrigeration equipment (calculated under Article 440).

The method is three steps: add the nameplate ratings of all qualifying kitchen equipment, multiply the total by the Table 120.56 factor for the number of units, and compare the result with the sum of the two largest units. The feeder demand is the greater of the two values.

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The Critical 'Two Largest Units' Rule in Action

The statutory condition in NEC 120.56 states: "In no case shall the feeder demand be less than the sum of the largest two kitchen equipment loads."

This rule frequently appears on the Minnesota journeyworker examination because it exposes candidates who blindly apply percentage multipliers without reading code footnotes and limitations.

Scenario A: Standard Proportionate Kitchen (Table Percentage Governs)

A cafeteria installs 6 pieces of kitchen equipment:

• Combi-oven: $14\text{ kW}$
• Conveyor dishwasher: $12\text{ kW}$
• Booster heater: $10\text{ kW}$
• Deep fryer: $10\text{ kW}$
• Griddle: $8\text{ kW}$
• Food warmer: $6\text{ kW}$

1. Total Connected Load: $14 + 12 + 10 + 10 + 8 + 6 = 60\text{ kW}$.
2. Apply Table 120.56 (6 units = 65%): $60\text{ kW} \times 0.65 = \mathbf{39\text{ kW}}$.
3. Check Statutory Floor (Two Largest): Largest two are $14\text{ kW} + 12\text{ kW} = \mathbf{26\text{ kW}}$.
4. Final Feeder Demand: Because $39\text{ kW} \ge 26\text{ kW}$, the calculated demand is $\mathbf{39\text{ kW}}$ ($39{,}000\text{ VA}$).

Scenario B: Disproportionate Kitchen (Statutory Floor Governs)

A specialty bakery installs 4 pieces of commercial equipment:

• Commercial deck baking oven: $30\text{ kW}$
• High-temp conveyor warewasher: $22\text{ kW}$
• Proofer cabinet: $3\text{ kW}$
• Countertop food warmer: $2\text{ kW}$

1. Total Connected Load: $30 + 22 + 3 + 2 = 57\text{ kW}$.
2. Apply Table 120.56 (4 units = 80%): $57\text{ kW} \times 0.80 = \mathbf{45.6\text{ kW}}$.
3. Check Statutory Floor (Two Largest): Largest two are $30\text{ kW} + 22\text{ kW} = \mathbf{52\text{ kW}}$.
4. Final Feeder Demand: Because $45.6\text{ kW} < 52\text{ kW}$, the statutory floor overrides the percentage calculation! The minimum feeder demand is $\mathbf{52\text{ kW}}$ ($52{,}000\text{ VA}$).

Exam Warning: Sizing this feeder for $45.6\text{ kW}$ violates NEC 120.56 and will fail an electrical inspection.

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Optional Calculation for Schools (NEC 120.86 & Table 120.86)

Under NEC Section 120.86, an optional calculation method is permitted for determining the feeder or service load for a school.

Statutory Eligibility Prerequisites

To utilize Section 120.86, the school building must meet the following criteria:

• Must be equipped with electric space heating, air conditioning, or both.
• If the school has no electric space heating or air conditioning (for example, gas-fired hydronic heat with no electric cooling), the optional method cannot be used; use the standard calculation.
• The connected load includes all interior and exterior lighting, power, water heating, cooking, other loads, and the larger of the air-conditioning or space-heating load.

Table 120.86 Demand Schedule

Demand factors are applied to the total connected load expressed in volt-amperes per square foot of interior floor area:

Complete Worked School Calculation

Calculate the service load for a $50{,}000\text{ sq ft}$ high school with a total connected load of $1{,}400{,}000\text{ VA}$ ($1{,}400\text{ kVA}$) supplied by a $480Y/277\text{ V}$, 3-phase, 4-wire system.

Step 1: Calculate Total Connected Load per Square Foot

$\text{Unit Connected Load} = \frac{1{,}400{,}000\text{ VA}}{50{,}000\text{ sq ft}} = 28\text{ VA/ft}^2$

Step 2: Apply Table 120.86 Demand Tiers

• Tier 1 (First $3\text{ VA/ft}^2$ at 100%): $50{,}000\text{ sq ft} \times 3\text{ VA/ft}^2 \times 1.00 = \mathbf{150{,}000\text{ VA}}$
• Tier 2 ($3\text{ to } 20\text{ VA/ft}^2$, representing $17\text{ VA/ft}^2$ at 75%): $50{,}000\text{ sq ft} \times 17\text{ VA/ft}^2 \times 0.75 = \mathbf{637{,}500\text{ VA}}$
• Tier 3 (Remainder over $20\text{ VA/ft}^2$, which is $28 - 20 = 8\text{ VA/ft}^2$ at 25%): $50{,}000\text{ sq ft} \times 8\text{ VA/ft}^2 \times 0.25 = \mathbf{100{,}000\text{ VA}}$

Step 3: Sum the Tiers for Total Demand

$\text{Net Calculated Service Demand} = 150{,}000\text{ VA} + 637{,}500\text{ VA} + 100{,}000\text{ VA} = \mathbf{887{,}500\text{ VA}} \quad (887.5\text{ kVA})$

Step 4: Calculate 3-Phase Service Current at 480V

$\text{Service Amperes} = \frac{887{,}500\text{ VA}}{\sqrt{3} \times 480\text{ V}} = \frac{887{,}500}{831.38} = \mathbf{1{,}067.5\text{ Amperes}}$

• Sizing Service Equipment: A standard 1,200-Ampere, 480Y/277V switchboard is specified.

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Optional Calculation for New Restaurants (NEC 120.88 & Table 120.88)

Under NEC Section 120.88, an alternative optional calculation is available for new restaurant services or feeders where the total connected load is known. Table 120.88 distinguishes between all-electric restaurants and not all-electric restaurants (those utilizing gas cooking/heating with electric auxiliaries):

Because of the sharp drop in the second bracket for all-electric facilities ($10\%$ between $201\text{ and } 325\text{ kVA}$), Section 120.88 frequently produces substantial reductions in required service ampacity compared to standard Part III methods.

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Practical Exam Scenarios & Trap Avoidance

Trap 1: Including Commercial Kitchen Exhaust Hood Fans in Table 120.56

• Scenario: A question lists five kitchen cooking appliances totaling $45\text{ kW}$ plus a $5\text{ HP}$ exhaust hood blower motor ($240\text{ V}$, $28\text{ A} = 6{,}720\text{ VA}$) and asks for the Table 120.56 demand load.
• Common Error: Lumping the exhaust fan motor into Table 120.56 as a 6th unit and multiplying $51.72\text{ kW} \times 0.65$.
• Correct Code Application: Ventilation motors are explicitly excluded from Table 120.56. Calculate the 5 kitchen appliances at $70\%$ under Table 120.56 ($45\text{ kW} \times 0.70 = 31.5\text{ kW}$), and calculate the ventilation fan motor separately under NEC Article 430 at $125\%$.

Trap 2: Incorrect Square Footage Tiering in Table 120.86

• Scenario: Calculating school demand by multiplying the entire connected load by $75\%$.
• Correct Code Application: Table 120.86 is tiered identically to progressive tax brackets. The first $3\text{ VA/ft}^2$ must be evaluated at $100\%$, the span between $3\text{ and } 20\text{ VA/ft}^2$ ($17\text{ VA/ft}^2$ maximum) at $75\%$, and only the excess over $20\text{ VA/ft}^2$ at $25\%$.