Three-prong outlets on two-wire cable
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A previous owner swapped the devices without running a ground. It tests as a false ground and it defeats surge protectors, which need a ground path to work at all. Either run a ground, or fit GFCI protection and label the outlets as ungrounded, which is what the code actually permits.
This is most common in homes built roughly 1940 to 1980. Post-war and mid-century — copper supply, aging cast iron stacks, 60 to 100 amp panels, first-generation central air.
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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
- No GFCI protection anywhere in the house
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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.