Quick Hits

⚡ Quick Hit: Single Appliances & Combo Circuits

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

Episode 21 — 120.55 Electric Cooking Appliances

🔧 THE QUICK HIT

We've made it through the big cooking-appliance rules.

But what happens when you're dealing with just one appliance?

Or maybe you've got a cooktop and multiple wall ovens sharing one branch circuit?

The notes to 120.55 cover these situations — and each one has a different approach.

🍳 NOTE 4 — ONE RANGE

What if you're calculating the branch-circuit load for a single range?

There's a specific cross-reference:

Table 220.55 is permitted.

⚠️ Notice the distinction:

This isn't telling you to use Table 120.55 for the single-range branch-circuit calculation.

It's pointing you to Table 220.55.

🔑 REMEMBER

One range

↓

Table 220.55 permitted

🔥 NOTE 5 — ONE WALL OVEN OR COOKTOP

Now take a single:

• Wall-mounted oven, or

• Counter-mounted cooking unit

when it's being considered by itself.

The branch-circuit load is simply:

THE NAMEPLATE RATING

No demand-factor table is needed for this particular calculation.

💡 SIMPLE

One wall oven → Nameplate

One counter-mounted cooking unit → Nameplate

🔌 NOTE 6 — COMBO ON ONE BRANCH CIRCUIT

Now things get interesting.

Suppose you have:

1️⃣ Counter-mounted cooking unit

PLUS

2️⃣ Up to two wall-mounted ovens

And they're:

• On the same branch circuit

• In the same room

What do you do?

🧮 ADD THEIR NAMEPLATE RATINGS

Then treat the combined rating:

AS ONE SINGLE RANGE

Example

Counter-mounted cooking unit:

6 kW

Wall oven #1:

4 kW

Wall oven #2:

5 kW

Combined nameplate rating:

6 + 4 + 5 = 15 kW

That combined 15 kW is treated as one range for purposes of the applicable calculation.

⚠️ THE GOTCHA

Don't treat the three appliances as three completely independent loads for this particular provision.

The rule specifically allows the combination to be treated as:

ONE RANGE

after adding their nameplate ratings.

🎯 TEST YOURSELF

A counter-mounted cooking unit and two wall-mounted ovens are all:

• In the same room

• On the same branch circuit

Per Note 6, how should their combined load be treated?

A) As 3 separate appliances, each calculated individually

B) As one range, using the sum of their nameplate ratings

C) Using Table 220.55 only

D) At 1¾ kW flat, regardless of nameplate rating

👇 What's your answer?

🧮 SHOW YOUR MATH

Suppose the appliances are rated:

Cooktop: 6 kW

Wall oven #1: 4 kW

Wall oven #2: 5 kW

Add the nameplates:

6 + 4 + 5 = 15 kW

Under Note 6, the combined rating is treated as:

ONE RANGE — 15 kW

✅ ANSWER

B) As one range, using the sum of their nameplate ratings

The counter-mounted cooking unit and up to two wall-mounted ovens can be combined when they're on the same branch circuit and in the same room.

Their nameplate ratings are added together and the combined load is treated as one single range.

🧠 120.55 — THE BIG PICTURE

You've now seen several different methods within the same section:

🍳 Larger Cooking Appliances

Use the applicable Table 120.55 methodology and its notes.

🔥 Smaller Cooking Appliances

The alternative method can use Column A or Column B under the applicable conditions.

🔧 One Range

Table 220.55 is permitted for the branch-circuit calculation.

⚡ One Wall Oven or Cooktop

Nameplate rating.

🔌 Cooktop + Up to 2 Wall Ovens

Add the nameplates and treat the combination as one range when the specified conditions are met.

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🧭 QUICK HIT NAVIGATION

← Back to Article 120 Quick Hits

← Episode 20 — The 1¾–8¾ kW Shortcut

→ Episode 22 — Instantaneous Water Heaters

⚠️ 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.

The National Electrical Code® and NEC® are registered trademarks of NFPA. JoshTheSparky.com is not affiliated with, sponsored by, or endorsed by NFPA.