How to Ground a Home Generator

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How to Ground a Generator and the Home Electrical System: Bonding the Generator to the Grounded Electrical System of the Home.

Grounding a Home Generator

Electrical Question: I have a 5500 watt generator I use as stand alone with extension cords inside off of the 2 GFCIs on the generator.

Existing Generator Installation:
The Outside Wall Has a Male Connection Receptacle L14-30p

  • I run thru a pass thru in the kitchen wall. On the inside wall is a 30Amp fused disconnect which then goes to an outlet box containing my L14-30r. Then from L1430 the power goes to my two GFCIs, then 120 volt extension cords. I have no desire to ever use a transfer switch and yes am fully aware never to BACK FEED branch circuits. In emergency I only want power for refrigeration, a small appliance and use the internet and two lights.
  • My question is about grounding. I run a #6 ground from the generator’s ground lug THRU AN OUTLET BOX on the outside into my basement and tied it with a Burndy into my Grounding electrode system #6 to a water pipe and 2 ground rods. Is this best? Would it be better to drive A SEPARATE Ground Rod at the generator?
  • My current reservation is that in the event of a lightning strike to the generator am I “inviting” the strike into my home’s GES, Grounding Electrode System? Thus a separate rod might help somewhat? Might avoid a hit to my GES with a separate ROD?
  • Also in the event of a fault inside the generator how does the fault clear…If a fault doesn’t trip the breaker could the ground (GES) become energized & back to the utility neutral/transformer. Thus would it be better to either use a separate ground rod or my GES? I am aware that the generator’s frame is a ground. Am I over doing this by grounding to GES or separate rod?
  • Lastly,another concern on my set up: Would any current in the event of a fault or lightning strike possibly get back to the electric utility pole transformer in addition to passing to ground thru my home GES. Thus making a separate rod a better choice?

Thanks for your availability & patience in helping. I have yet to find an example of anyone using my exact set up on-line and really would like to know if I should change anything.
This home electrical repairs question came from: Charlie, from Boston, Massachusetts.

Dave’s Reply:
Thanks for your electrical troubleshooting question Charlie.

How to Ground a Generator and the Home Electrical System

Skill Level: Advanced – Licensed Electrical Contractor, Not Recommended for Homeowners.
Tools Required: Electricians pouch of hand tools and the various power tools necessary for installing the generator and transfer switch.
Estimated Time: Depends on the type and size of the generator and transfer switch and the available access to the project area.
Important: Installing a generator and transfer switch or altering the home electrical system must be well thought out and performed with a permit with all work being inspected.

Bonding the Generator to the Grounded Electrical System of the Home

  • Installing an additional ground rod for a home generator would not be necessary when there will be an electrical connection to the home panel.
  • Installing a ground wire that is attached to the ground terminal of the generator or an internal bond, which is then attached to the bonded ground system of the home electrical panel is required.
  • In the event of a lighting strike, the strike will take the path of least resistance to the earth ground which should always be the home electrical ground system which has been installed according to applicable local and national electrical codes.
  • The path and power of a lightning strike is unpredictable due to many environmental factors, however  the required home Ground Electrode System GES is the best way to direct the lighting strike to the earth ground. This will also help prevent the lightning strike from traveling back to the utility transformer power pole.

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