60+ yr Old House – Three-Prong Outlets

Bootleg Ground

Improper Grounding

This post is about an electrical issue that is found all too often in older homes.  If a home is at least 60yrs old or so, then the wiring in the home is more than likely two wire conductor with no ground and the outlets should be a two-prong type.  This in itself is not necessarily an issue.  When I walk into an older home like this and I start seeing a more “modern” three-prong outlet, my suspicions begin.  Has the house been rewired or simply “upgraded” to a new outlet. Installing a three-prong outlet on a two wire system is a safety concern.  It creates the impression of ground protection when in fact there isn’t.

What is a ground connection you ask?

The ground connection provides a path back to a ground rod driven into the ground at the outside of the home and/or the water supply plumbing to carry a fault current away from the person using the appliance.  When you plug in an appliance, power tool or any device that has three prongs on the plug, that device relies on the ground connection to prevent possible electrocution.

In a few cases I have found what is called a bootlegged or false ground.  This is when a jumper wire is installed from the Neutral screw on the outlet to the Ground screw.  If you plug in a simple Three-Light outlet tester, it will show that the outlet is grounded.  A novice wiring the outlet may think this is not a problem since the Neutral and Ground connections are at the same electrical potential in the main panel.  This is a major electrical safety concern.  As mentioned in the last paragraph, a fault current from an electrical short needs to be carried as far away from the user as possible.

What are your options? 

Well, you can leave the two-prong outlet in place (or change the three-prong back to a two-prong outlet).  This is the least expensive option.  If you need a three-prong outlet for a specific appliance, then a licensed electrician can run a new grounded circuit.  Another option is to install a GFCI outlet (Ground Fault Circuit Interrupter).  This is option is allowed by the NEC (National Electrical Code) but it has its limitations.  It MUST be labeled with the “Non-Equipment Ground” sticker that comes with the outlet.  This will protect the user of the appliance from a ground fault electrical shock.  It will not; however, provide ground protection needed for sensitive electronic equipment.  Surge protectors for your entertainment system, computers or other sensitive electronics need a ground connection to protect the equipment.

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