GFI Protection in Ungrounded Homes

DALY CITY — Ground fault circuit interrupters (GFIs) are commonly used in bathrooms, kitchens and other areas where the presence of water brings an increased risk of electric shock. However, not everyone knows that GFIs are also a good protective measure in homes that aren’t grounded.

You can tell if a home’s electricity is grounded simply by looking at its outlets. If they only have two prongs, they’re not grounded—that’s what the third prong in a three-pronged outlet is for. Two-pronged outlets are common in homes that have old knob-and-tube wiring, which is a predecessor to today’s modern wiring.

In a home with ungrounded outlets, GFIs can literally be lifesavers. If a person gets electrocuted from an outlet that isn’t grounded, they’ll be exposed to the full voltage coming out of it, which may be up to 20 or 30 amps of electricity. A GFI breaker protects against this by measuring the voltage coming to and from the outlet and sensing when the electrical current is taking an unintended path, which is known as a “ground fault.” When the GFI senses a ground fault, it immediately trips to protect the user (the recipient of the current’s unintended path) from electrocution.

If your home’s electrical system isn’t grounded, the ideal solution is to replace your old knob-and-tube wiring with wiring that conforms to modern standards. However, if you can’t afford a whole-home rewire, consider the more affordable option of outfitting your outlets with GFIs. Either way, don’t put off resolving this dangerous state of affairs—call an electrician and get it taken care of as soon as possible.