Capacity, Load and Electrical Service Frequently Asked Questions

Are you planning for a new or upgraded electrical service? Are you interested in installing EV charging stations or heat pumps for your home or business? Understanding your property’s capacity and load is necessary — particularly if you have an older building. Seattle City Light is here to share what you need to know to help you power up your home or business.

As you plan for a new project, there are a few key terms to become familiar with:

  • Electrical Service is what brings electricity from City Light’s grid into your home or business.
  • Electrical Panel is a metal box that houses circuit breakers that control the flow of electricity throughout your home or business and is also known as a breaker box, load center, or service panel.
  • Capacity is the maximum amount of electrical power that a circuit, device, or electrical system can handle – such as the service from the power grid or the electrical panel in your building.
  • Load is the amount of electrical power used by devices, appliances, systems, or components connected to an electrical circuit.
    • Peak Load is the maximum amount of electrical power or energy consumed by a system, facility, home, or grid during a specific period.
    • Available Load is the amount of energy left over on your service, or panel, minus your peak load.

When customers ask about their capacity and load, they typically want to know if there is space on their current system for new or upgraded service. This could mean your electrical panel, electrical service, or capacity on the grid. To figure this out, you need to first understand what your project’s load will be. A load study will determine what capacity you’ll need.

Before adding additional electrical load to your property, hire a certified electrical consultant to do a load study. Your electrical contractor will examine:

  • the nameplate capacity of your existing equipment.
  • the equipment you want to install.
  • the square footage of your property.
  • the hours of occupancy.
  • other relevant information.

This examination will determine your new load for the project. Depending on this, you may already have sufficient capacity for additional loads that you want to add — such as EV car charging or heat pumps. If you don’t have sufficient capacity, you may have to upgrade your service size.

Please note that City Light does not provide customers’ load studies. We are responsible for providing you with the energy you need and maintaining the electrical infrastructure.

Yes, you can reduce the existing load at your property. City Light encourages customers to consider energy efficiency, energy management, and other strategies to reduce existing loads and peak energy needs of new loads. These strategies help reduce the need to upgrade customer service sizes.

For more information, visit Energy Efficiency Program Tools and Resources.

If you’ve done a load study, your electrician should be able to tell you your current capacity.

You can also find your existing capacity in several ways:

  • Refer to any Seattle City Light service letter issued regarding your service size.
  • Refer to your service entrance equipment nameplates and one-line diagrams.

If you don’t have access to these options, then reach out to your City Light representative.

Contact us if you have any questions about application requirements for your project. 

Yes, you can increase capacity at your property. This involves a request for new or upgraded electric service through City Light’s website.

If your anticipated load is more than available capacity, the first step in the process is to complete an application for electric service.

The application is your primary means of communicating the important details about your electrical project to Seattle City Light. The application for electric service must be completed online. You’ll need to provide specific details about the type and size of the electrical service you’re requesting. You’ll also be provided with a list of the necessary supporting documents to submit with your application, which vary depending on the type of project requested.

Before starting a new project or renovation, visit our Apply for New or Upgraded Electric Service page and review our requirements and standards resources. Find all applicable documents listed on the customer submittal checklist. This document is for your use in preparing the necessary documents for your project.

If I have questions about the application, you can call our intake desk at (206) 233-2777 to get assistance filling out the application.

The customer is responsible for electrical service installations and upgrades, including permits and inspections. City Light requires payment for services prior to completing the service connection. This cost may or may not be included by your contractor.

City light is only responsible for grid side upgrades. Please visit our Apply for New or Upgraded Electric Service page if unsure.

City Light offers incentives for transportation electrification projects that may cover additional costs.

For more information on Seattle City Light's electrification programs, visit Electrification.

City Light

Dawn Lindell, General Manager and CEO
Address: 700 5th Ave, Seattle, WA, 98104
Mailing Address: PO Box 34023, Seattle, WA, 98124-4023
Phone: (206) 684-3000

Seattle City Light was created by the citizens of Seattle in 1902 to provide affordable, reliable, and environmentally responsible electric power to the City of Seattle and neighboring suburbs.