Installing Sub-Panel Wiring

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 Subpanel

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 Subpanel Installation

Identifying Panel Circuits and Connected Loads

• Why a Subpanel is Installed
  • A subpanel is installed and used for several purposes including expanding the physical circuit capacity of the main electric panel when the main panel breaker space is at maximum capacity.
• Planning for a Subpanel
  • 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 Subpanel
  • Once the additional circuit loads have been identified then the amperage size of the subpanel may be determined.
• The Size of the Wire or Cable for the Subpanel
  • The size of the subpanel will determine the required size of electrical cable to be installed and the circuit breaker for the feeder circuit.
• Main Breaker for a Subpanel?
  
  • Attached Location (NEC Article 408.36)
    If the subpanel is installed in an attached area of a building a main breaker is not required if a breaker is provided at the panel which supplies power to the sub panel.
  • Detached Location ( NEC Article 225.21)
    If the subpanel is installed at a remote location, or at a detached building such as a detached garage or workshop then a main breaker is required if there are more than six circuit breakers that are installed.
• The Neutral and Grounding System
  
  • Attached Location (NEC Article 250.142)
    If a 120/240volt  subpanel is installed in an attached area of a building a four wire feeder must be installed which would include a separate ground wire, a separate neutral conductor, and two power conductors. The ground and neutral must be isolated, and a bonding jumper must not be installed from the neutral terminal to the subpanel enclosure.
  • Detached Location (NEC Article 250.32(a))
    If a 120/240volt  subpanel is installed at a detached building such as a detached garage or workshop, and there are more than one branch circuit, then the panel is actually consider to be a service panel, therefore a three wire feeder is installed which would include a neutral conductor, and two power conductors, and a ground system must be installed, such as a ground rod, UFER Ground, etc.. The ground and neutral must be isolated, and a bonding jumper must not be installed from the neutral terminal to the subpanel enclosure
• IMPORTANT
  • It is best to have a qualified electrical contractor install a subpanel project.
  • Sub panels should be installed by permit and receive the required inspections to ensure the project is installed correctly.

See 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

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 Subpanel

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 Subpanel Installation

Identifying Panel Circuits and Connected Loads

• Why a Subpanel is Installed
  • A subpanel is installed and used for several purposes including expanding the physical circuit capacity of the main electric panel when the main panel breaker space is at maximum capacity.
• Planning for a Subpanel
  • 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 Subpanel
  • Once the additional circuit loads have been identified then the amperage size of the subpanel may be determined.
• The Size of the Wire or Cable for the Subpanel
  • The size of the subpanel will determine the required size of electrical cable to be installed and the circuit breaker for the feeder circuit.
• Main Breaker for a Subpanel?
  
  • Attached Location (NEC Article 408.36)
    If the subpanel is installed in an attached area of a building a main breaker is not required if a breaker is provided at the panel which supplies power to the sub panel.
  • Detached Location ( NEC Article 225.21)
    If the subpanel is installed at a remote location, or at a detached building such as a detached garage or workshop then a main breaker is required if there are more than six circuit breakers that are installed.
• The Neutral and Grounding System
  
  • Attached Location (NEC Article 250.142)
    If a 120/240volt  subpanel is installed in an attached area of a building a four wire feeder must be installed which would include a separate ground wire, a separate neutral conductor, and two power conductors. The ground and neutral must be isolated, and a bonding jumper must not be installed from the neutral terminal to the subpanel enclosure.
  • Detached Location (NEC Article 250.32(a))
    If a 120/240volt  subpanel is installed at a detached building such as a detached garage or workshop, and there are more than one branch circuit, then the panel is actually consider to be a service panel, therefore a three wire feeder is installed which would include a neutral conductor, and two power conductors, and a ground system must be installed, such as a ground rod, UFER Ground, etc.. The ground and neutral must be isolated, and a bonding jumper must not be installed from the neutral terminal to the subpanel enclosure
• IMPORTANT
  • It is best to have a qualified electrical contractor install a subpanel project.
  • Sub panels should be installed by permit and receive the required inspections to ensure the project is installed correctly.

See 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

Installing a Sub-Panel
[ad#block]Electrical Question: I am installing a sub panel and have questions about the main wire connections.

•  Can I connect the sub-panel wires by the Main lugs, or do I need to go into a breaker first.
• Am I required to have only one separate ground rod?
• I am planning on getting this inspected also.

Thanks for your time!
Katie

This Electrical Wiring Question came from: Katie, a Homeowner from Roy, Washington.

Additional Comments: Great resource for a homeowner.

Dave’s Reply:

Thanks for your electrical wiring question Katie.

How to Install a Sub-Panel

Application: Wiring a Sub Panel
Skill Level: Intermediate to Advanced – Best installed by a Licensed Electrical Contractor, Danger of Arc Flash.
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.
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.

Installing a Electrical Sub-Panel and Planning the Circuits

• Installing a sub-panel is something that requires careful consideration and understanding in order for the project to be done safely and according to a list of applicable electrical codes, this is why I recommend that homeowners consult a qualified licensed electrical contractor to assist with a project of this nature.
• The main feeder cable wiring must be selected and sized properly and connected to a separate circuit breaker in the panel that is supplying the power to the sub-panel.
• There are several factors that must be considered when sizing and installing a sub-panel and a qualified electrician will be extremely helpful to identify these with you.

More about Wiring a Sub-Panel
Electrical Wiring Codes

• Home Electrical Codes

• Electrical Code Directory covering AFCI circuit, electrical-boxes, electrical-circuit, electrical-code-outlets, electrical GFCI, electrical-grounding
• Electrical-project, electrical-services, electrical-underground, electrical-wiring, electrical-wiring-code, lighting-codes and smoke-detectors.
  

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

Installing a Sub-Panel
[ad#block]Electrical Question: I am installing a sub panel and have questions about the main wire connections.

•  Can I connect the sub-panel wires by the Main lugs, or do I need to go into a breaker first.
• Am I required to have only one separate ground rod?
• I am planning on getting this inspected also.

Thanks for your time!
Katie

This Electrical Wiring Question came from: Katie, a Homeowner from Roy, Washington.

Additional Comments: Great resource for a homeowner.

Dave’s Reply:

Thanks for your electrical wiring question Katie.

How to Install a Sub-Panel

Application: Wiring a Sub Panel
Skill Level: Intermediate to Advanced – Best installed by a Licensed Electrical Contractor, Danger of Arc Flash.
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.
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.

Installing a Electrical Sub-Panel and Planning the Circuits

• Installing a sub-panel is something that requires careful consideration and understanding in order for the project to be done safely and according to a list of applicable electrical codes, this is why I recommend that homeowners consult a qualified licensed electrical contractor to assist with a project of this nature.
• The main feeder cable wiring must be selected and sized properly and connected to a separate circuit breaker in the panel that is supplying the power to the sub-panel.
• There are several factors that must be considered when sizing and installing a sub-panel and a qualified electrician will be extremely helpful to identify these with you.

More about Wiring a Sub-Panel
Electrical Wiring Codes

• Home Electrical Codes

• Electrical Code Directory covering AFCI circuit, electrical-boxes, electrical-circuit, electrical-code-outlets, electrical GFCI, electrical-grounding
• Electrical-project, electrical-services, electrical-underground, electrical-wiring, electrical-wiring-code, lighting-codes and smoke-detectors.
  

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

More about: Sub panel

• Installing a Sub Panel for a Detached Building
Do I need to run a ground wire for a 200 amp sub panel that is 200 feet away from the main panel? Grounding a Remote Sub Panel at a Detached Building.
Top of List DIY Home Electrical Wiring Projects


• Install an Electrical Sub Panel
Sub Panel installation | Thinking about installing a Sub Panel? Here is what must be considered first, and you may discover that you really do not need a sub panel at all.
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• What Size Main Disconnect Breaker in a Sub Panel
Can I use a 100amp main breaker in a 50amp sub panel? Options for a Main Disconnect Breaker in a Sub Panel.
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• Installing a Sub Panel for an Attached Garage Video
I am Planning and Installing a Garage Sub Panel for my Home: I want to add a panel to my attached garage, what size circuit breaker do I need?
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• Considerations When Planning An Electrical Sub Panel
How do I Plan for a Sub Panel Installation? Planning the right amperage and cabling for a sub-panel used in a basement, garage and other locations.
Top of List DIY Home Electrical Wiring Projects


• Planning for a Garage Electrical Sub Panel
How Can I Install Electrical Wiring and a Sub Panel in a Garage? Planning and Installing a Garage Sub Panel.
Top of List DIY Home Electrical Wiring Projects


• Neutral and Ground Wires in a Sub Panel
How to Configure the Neutral and Ground Wires in a Sub Panel - In a sub-panel the Neutral Wires must be separated from the Ground Wires and may not be terminated on the same buss, regardless if the ground wire is insulated or not.
Top of List DIY Home Electrical Wiring Projects


• Sub Panel Grounding and Neutrals
Understanding Grounding for Sub Panels: When you add a second electrical panel with separate neutral and common bars, do you ground the common to the box along with a ground rod connection?
Top of List DIY Home Electrical Wiring Projects