Installing a Sub Panel for an Attached Garage Video

I am Planning and Installing a Garage Sub Panel: I want to add a panel to my attached garage, what size circuit breaker do I need? © By: Dave Rongey

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Sub Panel in an Attached Garage
Electrical Question: I want to add a panel to my attached garage, what size breaker do I need?

• I have 200 amp service to my home at an outside panel that feeds into the home. I want to add a sub panel to my attached garage.
• The main is about 35 feet from where I would locate the sub-panel inside garage wall.
• I would run the 6/3 cable w/ground through the basement ceiling and through sill box into garage so it’s all indoor wiring.
• I have 2-15 amp circuits that currently feed a garage finished area for lights and workout equipment.
• I would like to pull these from the main and run them from the sub-panel along with a 240/30 amp feed for a heater that will run at 4000 watts and a separate 20 amp circuit for wall receptacle for a fridge.
• I may add a separate 20 amp circuit for wall receptacle in the future for tool use.
• The existing outlets are GFCI protected.

• My questions about installing the garage sub panel are:
  1. What size breaker do I need at the main to feed the sub ?
  2. Is 6/3 cable w/ground large enough to handle the loads?
  3. Does the new breaker at the main need to be GFCI to protect the 240 heater circuit?
• I plan on #10 to feed the heater from the sub, #12 to feed any 20 amp circuits from the sub and the 2 15’s I’ll be switching to the sub are currently 14-2 NMB. Am I missing anything?
• I’ve wired simple circuits from the main before but this will be new for me. I have some knowledge of electrical circuits as my father was an electrician but he is now disabled from a severe stroke and find myself in need of help to make sure I’m not doing anything that would compromise my family’s safety.

This electrical question came from: Vince, a Homeowner in Longmont, Colorado.

Additional Comments: This is a great site for safe wiring advice.

Dave’s Reply:
Thanks for your electrical question Vince.

Installing a Garage  Sub Panel

Application: Adding a Sub Panel to a Garage.
Skill Level: Intermediate to Advanced – Best performed by a Licensed Electrical Contractor, Panel work is Not Recommended for Homeowners.
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 for a Garage Sub Panel

• IMPORTANT: Before Installing a Garage Electrical Panel Consider the Following:
  
  • Identify the Circuits You Need
    Before installing a panel the loads must be identified, or at least the size of the panel must be determined.
  • Check the Main Panel
    Make sure the service panel that will supply the sub panel with the circuit has the amperage capacity and space for the additional circuit and breaker.
  • Select the Wire Type and Wiring Method
    Specify the type and size of electrical cable that will be used to get from the service panel to the sub panel.
  • Check the Wiring Path
    Identify the path that will be used to install the electrical cable from the service panel to the sub panel.
  • Outlets and GFCI Requirements
    Typically the circuit supplying the sub panel in an attached garage is not required to be GFCI.
  • Electrical Code Compliance
    Electrical circuits installed in the garage must be installed and protected by GFCI per NEC code, as it applies to the specific location and use.

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