GFCI requirements arrived progressively from the 1970s, so houses of this age often have none at all. Kitchens, bathrooms, garages, basements, laundry and exterior outlets are where it matters. On an ungrounded circuit a GFCI receptacle is still a legitimate and code-recognized improvement.

This is most common in homes built before about 1940. Pre-war construction — galvanized supply, cast iron drains, cloth-wrapped wiring, ungrounded circuits.

Related

• Federal Pacific or Zinsco panel
• Two-prong outlets throughout the house
• Cloth-covered cable visible in the attic or basement
• Fuse panel, or a 60 amp service
• Fuse larger than the wire it protects
• Ceiling fan mounted to a standard light box
• Knob-and-tube still energised
• Breakers or fuses that are not labeled

Back to Electrical.

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Written by Jaylan Jones. I Like To Fix earns a referral fee when a call connects to a contractor. See our business-model disclosure.