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Electrical Load Calculation

Online Interactive Residential Electrical Load Calculator


Summary: Residential Electrical Load Calculator, Online and Interactive provides accurate main service panel load calculations.
© By:

Quick Start Guide for the Electrical Load Calculator
Let's get started. Advanced
Experienced Electricians
No explanation needed.
Review the basics. Intermediate
Inspectors and Teachers
Short Explanations to help you get started.
Please explain the process. Novice
Homeowners and Students
Detailed explanations to help you get it right.

Please Note: This online calculating tool requires javascript to be turned on in your browser.

Detailed Instructions for the Electrical Load Calculator.

Introduction to the Electrical Load calculator

The purpose of the residential electrical load calculation is to accurately determine the size of the electrical service base upon the electrical equipment that will be installed. The national electrical codes are the basis of making sure the electrical service is sized properly and installed correctly.

Step 1

The General Electrical Load Requirements are based on the inside square feet area of the home which is then used to calculate the basic lighting load and required appliance circuits. The Residential Electrical Load Calculator is Pre-Loaded with electrical information for you to chose from. Click on the Question Mark Buttons for more specific information relating to each section and entry.

Step 2

Appliances and Motor Type Loads are typically larger equipment used in the kitchen, laundry room, garage. Be sure to check the nameplate information for accurate calculations.

Step 3

Heating and Air Conditioning. Properly Identifying Heating and Air Conditioning Equipment is very important because the equipment typically requires a larger electrical load.

Step 4

Perform the Calculations: The Calculate button will perform calculations from the information you have provided in this form. The Calculate Button Must Be Pressed when any changes are made to the form.

The Basics of How Electrical Power is Measured and Calculated

What is VA?

VA is the abbreviation for volt-ampere, which is a unit of power that is determined by multiplying the voltage and the amperage current in a circuit. VA is a standard measurement of electrical power that is used for identifying electrical circuit component requirements.
Example: a 120 volt circuit which is providing 1 ampere = 120 volt-amperes.

The Difference Between VA and Watts?

A watt is a measure of true power which is required to perform work at the rate of 1 joule per second. The wattage is calculated by multiplying voltage times the power factor of the circuit.
Example: Watts = Voltage times the Amperage times the Power Factor.

What is Power Factor?

PF or Power Factor is the ratio of the actual power in watts to the apparent power in volt-amperes which is expressed as a percentage.
Example: 100% power factor is the best , however a typical power factor could range between 75 to 90%.

In some areas of the form below you can combine VA loads for multiple equipment with the specified section.

Brief Instructions for the Electrical Load Calculator

The load calculator is divided into three main sections which enable you to enter the necessary information about the home project and the proposed electrical equipment that will be installed.

The calculations conform to the national electrical codes which focus on required loads and factoring in the appliance and motor equipment. The question mark help buttons will assist you with detailed information about typical equipment loads which may be selected in the various drop down menus.

This Residential Electrical Load Calculator is Pre-Loaded with electrical information for you to chose from. Please use additional Question Mark Buttons for more specific information. For your convenience the Update and Calculate Buttons will Recalculate the entire form.

Residential Electrical Load Calculator for the Main Service

This form and calculator has been updated and tested:
Posted: 2023-07-18
Questions or Comments: Feedback about this Form
Est. Minimum Size of the Electrical Service - 2020 NEC
Based upon NEC Articles 220.82(A), 220.82(B)(1), 220.82(B)(2), 220.82(C)

Step #1
General Electrical Load Requirements
Ref: NEC Article 220.82(B)(1)
Quantity Load Elect. Code & Information
Indoor Sq. Ft. Area of the Home - - -
Small Appliance Circuits 1500VA Ea.
Laundry Circuit 1500VA Ea.
Sec. #1 Sub-Total = - -

Step #2
Appliance & Motor Loads VA
Ref: NEC Article 220.82(B)(2)
Cook top Stove or Range
Cooking Unit / Microwave Oven
Water Heater
Hydro Massage Tub Motor
Garage Door Opener
Additional Appliance(s), Including EV Chargers
Sec. #2 Sub-Total = - -
Sec. #1 Sub-Total =
Sec. #1 and Sec. #2 Total =
First 10Kva @ 100% =
The Remaining 40% =
Adjustment 40% of Remainder =
Sec. #1 and Sec. #2 Adjusted Total = - -

Step #3
Heating & Air Conditioning VA
Ref: NEC Articles 220.82(B)(3) &(4), 220.82(C)
Single Source Heating Unit  
Heating and Air Conditioning Unit
OR Heat Pump without Supplemental Heat
Heating Unit with Supplemental Heat Source  
OR Supplemental Heating for Heat Pump
Heat Heat Pump
OR Separately Controlled -
Space Heaters VA Each
How Many Space Heaters
OR Continuous Electric Thermal Storage
Sec. #3 - Factors on the Highest Calculated Load : - -

Step #4
Perform the Calculations
Ref: NEC Article 220.82(A)
  - -
Calculated Total VA Load =
Calculated Total Amps Load =
Reset the Form - - -

© Copyright Dave Rongey

Click or Tap Here to Print This Page

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Did this help you? Send me your Feedback, Suggestions, or Requests

IMPORTANT: The calculating tools are provided as a guide to assist you to understand the process of accurately sizing a residential electrical panel based on proposed loads. The results of the calculations are based upon the accuracy of the information that you provide. The [Calculate] Button must be pressed when any changes are made to the form. Accurate load sizing is best performed by a professional architect or engineer which is reviewed by the building department in your jurisdiction. Calculations may vary depending on actual Air Conditioning and Heating loads which may require adjustments. This tool is based upon NEC codes, however it is not authorized or intended to replace or represent official NEC calculations.

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