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The Code Minute – Calculating Range Demand – S1E3 Art220Pt2 (Video)

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Electrical calculations are a critical part of an electrician’s job, and they are heavily tested on journeyman licensing exams. Understanding how to apply demand factors correctly can help you answer exam questions accurately and perform real-world electrical load calculations with confidence.

At Barts Electric, a national electrical construction contractor, we are committed to helping electricians and future electricians build their knowledge and advance their careers. In this article, we’ll walk through a common exam-style question involving the calculated demand load of an electric range and explain how to find the correct answer using the National Electrical Code (NEC).

The Question

A dwelling has a 7kW electric range. What is the calculated demand load?

  • 5,600 watts
  • 6,000 watts
  • 7,000 watts
  • 8,000 watts

The correct answer is 5,600 watts.

Let’s break down how to solve this problem.

Understanding the Key Phrase: Calculated Demand Load

The most important clue in this question is the phrase “calculated demand load.” When you see this terminology, it usually indicates that you need to perform a load calculation using the NEC rather than simply using the appliance’s nameplate rating.

For dwelling unit load calculations involving branch circuits, feeders, and services, the primary reference is NEC Article 220.

Finding the Correct NEC Reference

Start by navigating to Article 220, which covers:

  • General requirements
  • Branch-circuit load calculations
  • Feeder and service load calculations

For this question, you’ll need to look in Part II – Branch-Circuit Load Calculations.

Within this section, you’ll find requirements for electric cooking appliances, including household ranges.

The code states that household cooking appliances with loads exceeding 1¾ kW are permitted to be calculated in accordance with Table 220.55.

Since the range in our question is rated at 7 kW, it falls within this category, so Table 220.55 is the correct reference.

Using Table 220.55

Table 220.55 provides demand factors for household electric ranges and other cooking appliances.

Step 1: Determine the Number of Appliances

The question specifies only one range, so use the row for one appliance.

Step 2: Determine the Correct Column

The range is rated at 7 kW.

Looking at Table 220.55:

  • Column A applies to appliances less than 3½ kW.
  • Column B applies to appliances between 3½ kW and 8¾ kW.

Because 7 kW falls within that range, use Column B.

Step 3: Apply the Demand Factor

For one appliance in Column B, Table 220.55 allows an 80% demand factor.

Convert the range rating to watts:

7 kW = 7,000 watts

Apply the demand factor:

7,000 × 0.80 = 5,600 watts

Final Answer

Calculated Demand Load = 5,600 watts

Why Demand Factors Matter

The NEC recognizes that certain appliances are not always operating at their maximum load continuously. Demand factors allow electricians to size conductors, feeders, and services more accurately while maintaining safety and compliance.

Understanding when and how to apply demand factors is essential not only for passing licensing exams but also for performing accurate load calculations in the field.

Exam Tip

Whenever you see a question involving:

  • Electric ranges
  • Wall-mounted ovens
  • Counter-mounted cooking units
  • Household cooking appliances

Think of NEC Article 220 and Table 220.55. Knowing where to find these references quickly can save valuable time during an exam.

Build Your Career with Barts Electric

Barts Electric is a national electrical construction contractor dedicated to developing the next generation of skilled electricians. Whether you’re preparing for your journeyman exam, starting your career as an apprentice, or looking to advance as an experienced electrician, continuing education and code knowledge are key to success.

Barts Electric is always hiring motivated electrical apprentices and experienced journeymen who are ready to grow their careers in the electrical industry. If you’re interested in joining a company that values training, safety, and professional development, explore career opportunities with Barts Electric.

For more electrical exam preparation tips, NEC code discussions, and industry insights, be sure to watch the accompanying video and follow Barts Electric for additional educational content.

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Complete Video Transcript

Here’s a calculation style question that shows up on the exam. Let’s see if you know the answer.

A dwelling has a 7KW range. What is the calculated demand load? Is it 5600 watts, 6,000 watts, 7,000 watts, or 8,000 watts? Pause the video now to answer the question.

So, the answer is 5600 watts. Let’s talk about how we found this.

The big key word in this question is “calculated.” Calculated demand load. This is almost certainly referring to a calculation question.

There’s one article in particular that focuses on calculations for branch circuits, feeders, and services, and that’s Article 220.

So, if we open up our contents here, go to Chapter 2, Article 220, we’re going to see that Part One covers general requirements. Part Two covers branch circuit load calculations.

So, we’re going to go to Part Two.

Luckily, we have our tabs here. That takes us right to Article 220. Part One, general requirements. Part Two, branch circuit load calculations.

As we scroll through here, we’re going to quickly find electric cooking appliances. Ranges are electric cooking appliances.

So, if we read this, it says, “Applying demand factors for ranges, wall-mounted ovens, countermounted cooking units, and other household cooking appliances. Loads in excess of 1 and 3/4 kW shall be permitted in accordance with Table 220.55.”

So, we are referring to an appliance that is in excess of 1 and 3/4 kW. Right? We found out in the question that it’s a 7KW cooking appliance range. So, this is telling us to refer to Table 220.55.

Table 220.55, demand factors and loads for household electric ranges and other types of cooking units.

So, if we scroll here, on the far left column, we see number of appliances. This question only talked about one single appliance. So, we’re going to start with that number one.

Row number one tells us that we have one single appliance, and we’re going to go to Column A. Is it less than 3 1/2 kW? No, it’s not. Is it between 3 1/2KW and 8 and 3/4 kW? It’s a 7KW. So, that falls directly in between that range.

So, what we see here is the number of appliances is one, and because we fall under Column B, there is an 80% demand factor.

So, we’re going to take our 7,000 KW and take 80% of that demand, or multiply it by .8.

So, 7,000 multiplied by .8 is going to give us 5600 watts.

So, this question is telling us that there is a 7 kW, or 7,000 watt, range. We don’t have to take the entire 7,000 into the calculation. We can apply an 80% demand factor and only calculate 5600 watts for the demand.

Now you know how to find this kind of question.

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Complete Video Transcript

Here’s a calculation style question that shows up on the exam. Let’s see if you know the answer.

A dwelling has a 7KW range. What is the calculated demand load? Is it 5600 watts, 6,000 watts, 7,000 watts, or 8,000 watts? Pause the video now to answer the question.

So, the answer is 5600 watts. Let’s talk about how we found this.

The big key word in this question is “calculated.” Calculated demand load. This is almost certainly referring to a calculation question.

There’s one article in particular that focuses on calculations for branch circuits, feeders, and services, and that’s Article 220.

So, if we open up our contents here, go to Chapter 2, Article 220, we’re going to see that Part One covers general requirements. Part Two covers branch circuit load calculations.

So, we’re going to go to Part Two.

Luckily, we have our tabs here. That takes us right to Article 220. Part One, general requirements. Part Two, branch circuit load calculations.

As we scroll through here, we’re going to quickly find electric cooking appliances. Ranges are electric cooking appliances.

So, if we read this, it says, “Applying demand factors for ranges, wall-mounted ovens, countermounted cooking units, and other household cooking appliances. Loads in excess of 1 and 3/4 kW shall be permitted in accordance with Table 220.55.”

So, we are referring to an appliance that is in excess of 1 and 3/4 kW. Right? We found out in the question that it’s a 7KW cooking appliance range. So, this is telling us to refer to Table 220.55.

Table 220.55, demand factors and loads for household electric ranges and other types of cooking units.

So, if we scroll here, on the far left column, we see number of appliances. This question only talked about one single appliance. So, we’re going to start with that number one.

Row number one tells us that we have one single appliance, and we’re going to go to Column A. Is it less than 3 1/2 kW? No, it’s not. Is it between 3 1/2KW and 8 and 3/4 kW? It’s a 7KW. So, that falls directly in between that range.

So, what we see here is the number of appliances is one, and because we fall under Column B, there is an 80% demand factor.

So, we’re going to take our 7,000 KW and take 80% of that demand, or multiply it by .8.

So, 7,000 multiplied by .8 is going to give us 5600 watts.

So, this question is telling us that there is a 7 kW, or 7,000 watt, range. We don’t have to take the entire 7,000 into the calculation. We can apply an 80% demand factor and only calculate 5600 watts for the demand.

Now you know how to find this kind of question.