Quick Hits

⚡ Quick Hit: Cooking Appliances — The Base Rule

NEC Article 120 — “Load Calcs Won't Kill You” 🔌⚡

Episode 18 — 120.55 Electric Cooking Appliances

🍳 THE QUICK HIT

Ranges, ovens, cooktops, and other household cooking appliances don't simply get thrown into a basic nameplate calculation.

For qualifying cooking equipment, 120.55 provides a specific calculation method using Table 120.55.

Let's start with the foundation.

📖 120.55 — Electric Cooking Appliances

The provisions apply to household electric cooking appliances such as:

• Household electric ranges

• Wall-mounted ovens

• Counter-mounted cooking units

• Other household cooking appliances

when they are rated over 1¾ kW.

⚡ THE BASIC RULE

Qualifying cooking appliances can be calculated using:

TABLE 120.55

Rather than simply using each appliance's individual nameplate rating at full value.

🧮 kW = kVA

For this calculation:

1 kW = 1 kVA

No additional power-factor conversion is needed for the calculation method described here.

💡 REMEMBER

Don't overcomplicate it.

If the appliance is rated in kW, that value can be treated as the corresponding kVA value for this calculation.

🏫 INSTRUCTIONAL PROGRAMS

The provisions aren't limited strictly to residential kitchens.

The cooking-appliance calculation can also apply to cooking appliances used in instructional programs.

Example

A school kitchen used for a home-economics or similar instructional program may have cooking appliances that fall under this provision.

⚡ THE 3-PHASE TWIST

Here's another phase-distribution rule to remember.

When there are two or more single-phase cooking appliances supplied by a 3-phase, 4-wire feeder or service, the calculated load is based on:

2 × the maximum number of appliances connected between any two phases

🧠 WHY?

The calculation accounts for how the single-phase cooking appliances are distributed across the three phases.

So don't automatically assume:

Add every appliance together

Instead, identify the maximum number connected between any two phases, then apply the required multiplier.

🎯 TEST YOURSELF

Per 120.55, which of these appliances is Table 120.55 designed to cover?

A) Only appliances rated exactly 1¾ kW

B) Any household cooking appliance rated MORE than 1¾ kW

C) Only ranges, never ovens or cooktops

D) Only commercial cooking equipment

👇 What's your answer?

✅ ANSWER

B) Any household cooking appliance rated MORE than 1¾ kW

The provision covers qualifying household electric cooking appliances rated over 1¾ kW, including ranges, wall-mounted ovens, counter-mounted cooking units, and other household cooking appliances covered by the section.

🔑 THE TAKEAWAY

120.55 = Cooking Appliances

Over 1¾ kW

↓

Use Table 120.55

↓

kW = kVA for this calculation

And remember the special 3-phase, 4-wire rule when multiple single-phase cooking appliances are involved.

⚠️ TABLE 120.55 NOTE

The actual Column A, Column B, and Column C demand-factor values of Table 120.55 are not reproduced here because the table itself was not available in the source material used for this Quick Hit.

This episode therefore explains the methodology and requirements described in the available material rather than supplying unverified demand-factor percentages.

For the exact applicable demand-factor values, consult the official NEC and the complete Table 120.55.

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🧭 QUICK HIT NAVIGATION

← Back to Article 120 Quick Hits

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→ Episode 19 — Cooking Appliance Demand Factors

⚠️ EDUCATIONAL NOTICE

This Quick Hit is an educational explanation based on the author's understanding of the NEC. It is not a substitute for the official NEC, applicable local amendments, manufacturer instructions, or the determination of the Authority Having Jurisdiction (AHJ).

Always verify the requirements applicable to your specific installation.

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