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Replacing Ungrounded Outlets with a GFI

Replacing Ungrounded 2-Prong Outlets with a Standard 3-Prong Outlet, Replacing Ungrounded 2-Prong Outlets with a GFCI Outlet.

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GFI Outlets and Ungrounded Outlets – What Is Legal and Safe
Electrical Question: Does a GFCI outlet need a ground wire to function properly or protect from Ground faults?

This electrical wiring question came from: Jeff, a Handyman from Lancaster, Pennsylvania.

Dave’s Reply:
Thanks for your electrical wiring question Jeff.

Application: Replacing Outlets with GFCI Outlets.
Skill Level: Beginner to Intermediate – Best if wired by a Licensed Electrical Contractor.
Tools Required: Basic Electricians Pouch Hand Tools and a Voltage Tester.
Estimated Time: Depends on personal level experience, ability to work with tools and the number of GFI outlets that will be installed.
Precaution: Identify the affected outlet circuits at the electric panel, turn them OFF and Tag it with a Note before working with the outlet wiring.
Notice: Replacing outlets or installing GFCI Outlets should be done according to local and national electrical Codes.
Materials: Make sure to use materials of the same amperage and voltage rating as the electrical circuit.

How a GFI Outlet may be Installed In Place of  an Ungrounded Outlet

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FAQs Frequently Asked Questions and Comments

3 Responses to “Replacing Ungrounded Outlets with a GFI”
  1. Phelectrical says:

    You can install a GFCI and have it protect 20 outlets that are ungrounded, and make them all 3 prong outlets. This can also be achieved with a GFCI breaker, instead of the GFCI outlet, which is almost always easier on an old knob and tube style house.

  2. Dave Rongey says:

    Hi Mike,
    Unfortunately, installing a 3wire outlet where a ground wire is not present is technically against the code, and they should all be replaced with 2wire outlets. Installing a GFCI outlet in locations where they are required is acceptable as described in the article above, however this practice still does not provide a ground path of any type, it simply provides ground fault protection for that location. In this example, additional outlets may not be connected to that GFCI outlet because there will be no way for the ground sensing circuitry of the GFCI outlet to be extended to the additional outlets, therefore there will be no ground fault protection to additional outlets. With an older home such as this a separate bonded ground wire system may be installed to outlets so they may have a 3wire receptacle outlet installed, however the effort and resources might be best used to upgrade the electrical wiring of the home, at least one area at a time. Special consideration should also be given to the main panel and electrical system integrity as well, along with making sure the home has all the required smoke detectors.
    I hope this helps you with your home project.
    Be Safe,

  3. Mike says:

    I purchased an older house that has a two wire system with no ground. The two slot receptacles have been replaced with the three hole type with no ground wire. Without rewiring the house how can the receptacles be protected and be safe? Can one GFI be used to protect 3 to 4 receptacles as long as they are on the same circuit? If they can which receptacle does the GFI need to installed on, or does it matter?

    Thanks in advance for your help.