Navigating Home Electrical Service Sizes

Modern homes are equipped with an ever-increasing number of electrical devices and appliances. From air conditioning units to high-end kitchen appliances and charging stations for electric cars, the demand for electricity in homes is at an all-time high. Let’s break down electrical sizing together and get an understanding of how to properly size your home's electrical service to keep things safe (we don’t need to start any fires) but also run efficiently. 
Disclaimer: Grover is dedicated to providing helpful information and quality products. However, we are not responsible for any damage or injury resulting from electrical work. Always hire a professional for installation and adhere to local regulations. This guide is designed to give you a foundational understanding of choosing the right electrical service size, but nothing replaces professional advice tailored to your specific situation. We suggest you review Article 220 and the examples in Chapter 9 of the National Electrical Code to obtain more information about service requirements. Also, check with your local governing authorities for more information. 

The Importance of Proper Sizing

Electrical service that is too small can lead to frequent circuit breaker trips and potential safety hazards like fires. On the other hand, excessively large electrical service can be unnecessarily expensive, both in installation and energy wastage. So, choosing the right size is about finding the balance that fits your home’s specific needs.

Standard Electrical Service Sizes

  • 100 Amps: Ideal for smaller homes with fewer electrical demands. Suitable if major appliances like heating and cooking are gas-operated.
  • 200 Amps: The most common size for average homes that use a mix of electrical and gas appliances. It comfortably supports modern appliances, including HVAC systems and electric vehicle chargers.
  • 400 Amps: Recommended for large homes with high electrical usage, including multiple HVAC units, advanced home automation systems, and additional luxury amenities such as pools and large hot tubs.

Calculating Your Home's Electrical Needs

To accurately determine what size service your home requires, you'll need to calculate the total load of all the electrical devices and appliances you plan to use. Here’s a simplified process based on the 2005 National Electrical Code:
  1. List all your appliances and their wattage. Include lighting, HVAC, kitchen appliances, and any specialty equipment like home theaters or workshops.
  2. Apply demand factors according to NEC guidelines. This helps adjust the raw total to reflect that not all devices will be operating at full capacity simultaneously.
  3. Divide the adjusted total by 240 volts to convert the wattage into amperage, which is what service sizes are measured in.

Grover's Simplified Service Size Chart

To help you get started, here’s a basic chart inspired by the NEC guidelines. This chart should be used as a starting point; for detailed planning, consult a professional. 
Load Type Load Calculation Basis Example Calculation
General Lighting/Receptacle Square footage x 3 Watts/SF 1,500 SF home x 3 Watts/SF = 4,500W
Small Appliance Circuits Number of circuits x 1,500 Watts 2 circuits x 1,500 Watts = 3,000W
Laundry Circuits Number of circuits x 1,500 Watts 1 circuit x 1,500 Watts = 1,500W
Fixed Appliances Nameplate rating Water Heater = 4,500W
HVAC and Heat Pumps Nameplate rating (100% for heat pump, 65% for supplemental) AC = 5,000W, Heater (65%) = 3,250W
Add up all the watts from your calculations and then adjust for demand as per NEC guidelines. Finally, divide by 240 volts to find your service size in amps.

Expert Consultation and Local Codes

Always consult with a licensed electrician to finalize your service size, especially since local codes and standards can significantly influence the requirements. Grover experts are available to help guide you through this process, ensuring you make the most informed decisions tailored to your home's specific needs. PDF Download for Reference 
Visit Your Closest Store


Call Us: (360) 574-3134

1900 NE 78th Street

Vancouver, WA 98665

Get Directions Store Details All Locations
01NAMPAhi scaled e1718925460254
Klamath Falls
Grants Pass
Vancouver 03 2015 web