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.
Grounding a Sub Panel at a Detached Building
Electrical Question #1: Do I need to run a ground wire for a 200 amp sub panel that is 200 feet away from the main panel?
- My question is about Grounding a Sub-Panel: I am installing a 200 amp sub panel to an existing structure that is 200 plus feet away from the main panel.
- The structure has a uffer ground rod installed, (20 foot rebar tied to the main slab / footing rebar) and I can install secondary grounded rod as well outside.
- Question: can the structure stand alone with its own grounding system? or do I need to run a ground wire back to the main panel.
- I am Using 2/0 copper wire in PVC conduit buried to get from the main panel to the structure.
This electrical wiring question came from Dennis, in Placereville, California.
Electrical Question #2:
What is the proper way to run an electrical supply to a sub panel in a barn or outbuilding?
This electrical wiring question came from Chris, a Handyman in Johns Creek, Georgia.
Thank you for your electrical wiring questions.
Grounding a Remote Sub Panel at a Detached Building
Application: Installing a Sub Panel for a Separate Building.
Skill Level: Advanced – Licensed Electrical Contractor – Not Recommended for Homeowners.
Tools Required: Electricians pouch of hand tools and the various power tools necessary for the specific method of electrical service installation.
Estimated Time: Depends on the type of panel, the location, and available access to the project area.
Precaution: This is an extensive project. Working in an electric panel has possible arc flash hazards and should be performed by a Licensed Electrical Contractor.
Notice: Installing an Electrical Service Panel must be done according to local and national electrical codes with a permit and be inspected.
Grounding a Sub Panel 200 Feet from the Main Panel
Electrical codes and information that should be considered when installing an electrical sub panel at a remote building.
- The Grounding System for a Separate Structure
- A ground wire is not required in the conduit that is feeding power to the panel at the separate structure.
- A GES, Grounding Electrode System must be provided at the separate structure for the sub panel.
- Grounding electrode conductors for the remote panel must be sized per NEC Table 250.66
- As per NEC Article 250.32-B-1 – Do Not install a bonding jumper to the neutral bar. Make sure to isolate the grounds and neutrals separately.
- NEC Article 225.31 – A main breaker must be installed if there are more than six circuit breakers in the sub panel.
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Consult your Local Building Department about Permits and Inspections for all Electric Wiring Projects.