Pre-1965 non-metallic cable used cloth and rubber insulation that embrittles and falls away from the conductor, especially where it has run warm. Once the insulation is crumbling at the panel or at boxes, the circuit needs replacing rather than repairing.

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
• 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
• Breakers or fuses that are not labeled

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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.