Knob and Tube Wiring
Higher Review PriorityHow it looks
Single conductors run separately on porcelain knobs and pass through framing with porcelain tubes. It usually appears on exposed basement joists or in attics.
Typical years
Common in older homes and generally associated with installations dating to the 1950s or earlier.
Where to look
Unfinished basements, attics, open framing, and areas where old circuits are visible before they disappear into finished walls.
Why it matters
Older systems may not provide grounding and can raise insurance or renovation concerns. Homes with knob and tube wiring often also have ungrounded outlets.