# Mastering Residential Load Calculations for the 2026 NEC: Step-by-Step Examples for Texas Exams
I'm going to walk you through residential load calculations the way I'd explain them to an apprentice on the job. These calculations are bread and butter for passing the Texas electrical exams—they show up on every single test, and you need to be solid on them.
Why Residential Load Calculations Matter for Your Texas Exam
Let me be straight with you: if you can't do load calculations by hand, you're going to struggle on the exam. The testing authorities in Texas expect you to understand why you're doing each step, not just punch numbers into a formula. That's especially true for the calculations portion, which is where many candidates lose points.
The 2026 NEC hasn't made dramatic changes to Article 220 (which covers load calculations), but there are some clarifications and refinements you need to know. My job here is to show you the method that works every single time.
The Three-Step Method for Residential Load Calculations
Every residential load calculation follows the same logic:
- List all connected loads (in watts or amperes)
- Apply demand factors from NEC Article 220
- Size your service or feeder based on the calculated demand load
Step 1: Understanding Connected Load vs. Demand Load
This is where most people get confused, so pay attention.
Connected load is everything that could run in your house at the same time. Your air conditioner, electric range, water heater, lighting, refrigerator—add it all up.
Demand load is what the NEC expects you to actually plan for. You're not going to run your electric range at full capacity while simultaneously charging an electric vehicle, running the air conditioner, and heating water. The NEC recognizes this, so it lets you apply demand factors—basically percentage reductions—to some loads.
This is where NEC Article 220 comes in. It's your roadmap.
Step 2: Know Your Load Categories
The 2026 NEC breaks residential loads into categories, and each one gets a different treatment:
- General lighting and small appliances – subject to demand factors
- Electric range, wall-mounted ovens, and cooktops – subject to demand factors per NEC 220.55
- Electric water heaters, air conditioners, and heat pumps – usually not subject to demand factors (they're treated as full load)
- Dryers – subject to demand factors per NEC 220.54
- Fixed space heating or air conditioning – the larger of the two, not both
Worked Example #1: Single-Family Dwelling (Basic Load Calculation)
Let's calculate the service size for a typical 2,000 sq. ft. residential home in Texas.
Given information:
- House size: 2,000 square feet
- 120/240V single-phase service
- Electric range (12 kW)
- Electric water heater (4.5 kW)
- Air conditioning (4 tons, approximately 12 kW)
- Electric dryer (5.5 kW)
- General lighting and small appliances (to be calculated)
Per NEC 220.12, general lighting is calculated at 3 watts per square foot for dwellings.
General lighting: 2,000 sq ft × 3 W/sq ft = 6,000 watts
Per NEC 220.52, we need two small appliance circuits (minimum 1,500 watts each) and one laundry circuit (minimum 1,500 watts).
Small appliances: 1,500 W + 1,500 W = 3,000 watts Laundry circuit: 1,500 watts
Total general loads (before demand factor): 6,000 + 3,000 + 1,500 = 10,500 watts
Step 2: Apply demand factor to general loads
Per NEC 220.42, the first 10,000 watts of general lighting and small appliance loads use a 100% demand factor. Anything over 10,000 watts uses a 25% demand factor.
- First 10,000 W × 100% = 10,000 W
- Remaining 500 W × 25% = 125 W
Step 3: Calculate the larger of heating or cooling load
In Texas, air conditioning is almost always larger than heating, so we use the AC load.
Per NEC 220.60, air conditioning loads are typically calculated at 100% (no demand factor).
Air conditioning demand: 12,000 watts
Note: We do not add heating load because we only use the larger of the two.
Step 4: List other loads at 100% (no demand factor)
These loads don't get demand factors:
- Electric water heater: 4,500 W × 100% = 4,500 watts
- Dryer: Per NEC 220.54, if nameplate is 5.5 kW, we use 5,500 watts (these do have a demand factor, but let me show you that next)
Electric range: Per NEC 220.55, for a single range of 12 kW (or less), we use 8 kW as the demand load. (This changes when you have multiple ranges, but for this example, it's a single range.)
Electric range demand: 8,000 watts
Step 5: Add up all demand loads
- General lighting and small appliances: 10,125 W
- Air conditioning: 12,000 W
- Water heater: 4,500 W
- Dryer: 5,500 W
- Range: 8,000 W
Step 6: Convert to amperes and size the service
Total demand load: 40,125 W ÷ 240 V = 167.2 amperes
Per NEC 230.79, the minimum service size for a single-family dwelling is 100 amperes, but we've calculated 167.2 amperes. The next standard service size above 167.2 A is 200 amperes.
Answer: This home requires a 200-amp service.
Worked Example #2: Dwelling with Continuous Loads (Advanced)
Now let's make it harder. Let's say this same home has a built-in sauna (continuous load) that's rated 10 kW.
Continuous loads are game-changers. Per NEC 215.2 and 230.42, continuous loads must be sized at 125% of the load.
Previously calculated total: 40,125 W Sauna load (continuous): 10,000 W × 1.25 = 12,500 W
New total calculated load: 40,125 + 12,500 = 52,625 watts
In amperes: 52,625 W ÷ 240 V = 219.3 amperes
The next standard service size is 225 amperes (or 250 amperes for some manufacturers).
This is a critical detail on the exam: forgetting to multiply continuous loads by 125% will cost you points.
Worked Example #3: Dwelling with Electric Vehicle Charging Station
Tesla and electric vehicles are everywhere in Texas now. Let's add an EV charging station rated at 40 amperes at 240V.
40 A × 240 V = 9,600 watts
If the charging station is hardwired and expected to be in use regularly, this is a continuous load per NEC Article 625 and would be calculated at:
9,600 W × 1.25 = 12,000 watts
New total calculated load: 40,125 + 12,000 = 52,125 watts
In amperes: 52,125 W ÷ 240 V = 217.2 amperes
Again, a 225-amp or 250-amp service would be required.
Common 2026 NEC Points to Remember
Nameplate vs. Rating
Per NEC 220.55, if a range's nameplate rating is over 12 kW, you can use the formula approach:- 8,000 watts + (nameplate kW − 12 kW) × 5%
Demand Factors Apply to Specific Categories
The 25% demand factor for general lighting (NEC 220.42) does not apply to fixed appliances. Don't mix them up.Never Double-Count Loads
If a load is already included in your general load calculation, don't add it again as a separate circuit. I see this mistake all the time.Motor Loads
If the exam includes a large motor (like a pool pump), per NEC 430.24, add 25% to the motor's full-load current. This is separate from your general calculations.Exam Tip: Show Your Work
On Texas electrical exams, you get partial credit for showing your work. Even if your final answer is off, if the examiner can see you're using the right method and formula, you'll pick up points.
Write out:
- What loads you identified
- Which demand factors you applied and why
- Your arithmetic step-by-step
- Your final answer with the unit (watts or amps)
What to Bring to the Exam
Make sure you understand these NEC sections by heart:
- NEC 220.12 – General lighting calculation (3 W/sq ft for dwellings)
- NEC 220.42 – Demand factors for general loads
- NEC 220.52 – Small appliance and laundry circuits
- NEC 220.54 – Dryer demand load
- NEC 220.55 – Range and cooktop demand load
- NEC 220.60 – Air conditioning and heating (use the larger, not both)
- NEC 215.2 and 230.42 – Continuous load sizing at 125%
Practice Problems for You
Before you take the exam, try these on your own:
- Calculate the service size for a 1,500 sq ft home with a 10 kW range, 3.5 kW water heater, and 3.5-ton AC (12.5 kW equivalent).
- Same house, but add a 50-amp continuous EV charger. What service size now?
- A home has two electric ranges in a common kitchen area. The first is 12 kW, the second is 14 kW. What's the total demand load for both ranges per NEC 220.55?
Final Thoughts
Residential load calculations aren't mystery math. They're a systematic process that the NEC has laid out clearly. Master the three steps—list loads, apply demand factors, size the service—and you'll nail this portion of the Texas electrical exam every time.
The examiners want to see that you understand why demand factors exist (because not everything runs at once) and that you can apply them correctly and consistently.
Now go practice. You've got this.