How to Plan for a Sub Panel

By Dave Rongey - Summary:

Planning for an Electric Sub Panel: Identifying Panel Circuits and Connected Loads. Sub Panels are installed and used for several reasons including expanding the circuit breaker capacity of the main electrical panel.

Sub Panels for Expanding Circuit Capacity

Electrical Question: Can I branch out to another small panel board from the main panel board to separate some appliance circuits?

  • I’m planning to branch out one of the 30amp circuits in the main panel board.
  • I would like to add a new panel board.
  • The Circuits that will be installed:
    • One 30amp breaker as the main disconnect.
    • Two 20amp breakers for branch circuits.

This electrical question came from: Art, from Kansas City, Missouri.

Dave’s Reply:
Thanks for your electric wiring question Art.

Adding a Sub Panel

Application: Adding a Sub Panel.
Skill Level: Intermediate to Advanced – Best performed by a Licensed Electrical Contractor.
Tools Required: Electricians pouch of hand tools and the various power tools necessary for installing the sub-panel.
Estimated Time: Depends on the type and size of the panel and available access to the project area.
Precaution: Any existing electrical wiring within the immediate area that may interfere with the installation of the sub panel should be identified and turned OFF and Tagged if necessary. Working in an electric panel is dangerous due to arc flash hazards and the possibility of electric shock.
Notice: Installing additional electrical wiring and a sub-panel should be done according to local and national electrical codes with a permit and be inspected.

Planning a Sub Panel Installation

Identifying Panel Circuits and Connected Loads

  • Why Sub Panels are Installed
    • Sub Panels are installed and used for several purposes including expanding the physical circuit capacity of the main electric panel.
  • Planning for a Sub Panel
    • Planning for the sub panel is extremely important for the project to be successful.
    • All of the potential circuit loads for the new sub panel need to be identified.
  • The Capacity of the Main Electrical Panel
    • Main The electrical load capacity of the main electrical panel must be able to support the existing loads and the proposed additional loads.
  • The Size of a Sub Panel
    • Once the additional circuit loads have been identified then the amperage size of the sub panel may be determined.
  • The Size of the Wire or Cable for the Sub Panel
    • The size of the sub panel will determine the required size of electrical cable to be installed and the circuit breaker for the feeder circuit.
    • It is best to have a qualified electrical contractor install a sub panel project.
    • Sub panels should be installed by permit and receive the required inspections to ensure the project is installed correctly.

More about Electrical Wiring

Basic House Wiring Circuits

  • House Wiring Circuits and Circuit Breakers

  • This article looks at common 120 volt and 240 volt house wiring circuits and the circuit breakers that are installed identifying the types and amperage sizes used in most homes.

Electrical Panel Circuit Listing

Electrical Circuit Breakers

  • Home Electrical Circuit Breakers

  • A guide to home electrical circuit breakers and how they work to protect your electrical wiring. When properly installed, your home electrical wiring is protected by a circuit protection device.

Home Electrical Wiring Plan

Basic Home Wiring Diagrams

Learn How to Wire it Right with my
Complete Guide to Home Electrical Wiring
Perfect for Homeowners, Students,
Handyman, Handywomen, and Electricians
Wiring GFCI Outlets
Wiring Home Electrical Circuits
120 Volt and 240 Volt Outlet Circuits
Wiring 3-Wire and 4-Wire Electric Range
Wiring 3-Wire and 4-Wire Dryer Cord and Dryer Outlet
How to Troubleshoot and Repair Electrical Wiring
Wiring Methods for Upgrading Electrical Wiring
Electrical Codes for Home Electrical Wiring
....and much more.

» Click here to learn more about Home Electrical Wiring «
  repair electrical wiring  

Be Careful and Be Safe - Never Work on Energized Circuits!
Consult your Local Building Department about Permits and Inspections for all projects.


Click the banner to Ask a Detailed Electrical Question and get an Instant Reply:
electrical question


If you are asking a Quick Question please make sure it is about This TOPIC:
“How to Plan for a Sub Panel”

Comments Posted here are Open for Quality Discussion and Participation.