How to Tell if a House Has Knob-and-Tube Wiring

Knob-and-tube systems used individual conductors supported on porcelain knobs and passed through framing in porcelain tubes. Attics and unfinished basements are common places to see exposed portions of old systems.

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Common visual clues

Look for separate cloth-covered conductors, round porcelain knobs supporting wire along framing, and porcelain tubes where conductors pass through joists or studs.

Old parts may remain after rewiring

Porcelain components or clipped wire can remain after circuits are abandoned. Visual identification is useful, but it does not determine whether a conductor is energized.

What to do next

If the wiring may be active, avoid moving or modifying it. An electrical evaluation can establish the condition and extent before you plan work around it.

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Talk about your Providence property

Call and tell us what you found, where the old wiring is visible, and what work you are planning.

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