Definition
Early 1900s wiring method using ceramic knobs — ungrounded; often requires replacement in active circuits.
Why is knob-and-tube a problem if it worked for a century?
Three reasons age can't fix: it has no ground, so surge strips and three-prong safety assumptions don't actually protect anything; its free-air design fails when blown-in insulation buries the conductors, trapping heat; and a century of splices, brittle sheathing, and amateur taps leaves the circuit's true condition unknown. Many insurers surcharge or decline homes with active K&T, which is often what forces the decision.
Does it all have to come out at once?
Usually no. A licensed assessment maps which circuits are genuinely live K&T versus already-replaced runs, then replacement is staged — worst and most-loaded circuits first, coordinated with any planned panel work so walls open once. Buying or selling a pre-1940s home is the natural moment to price the staged plan.
What does replacing knob-and-tube actually involve?
Electricians fish new grounded cable through walls and ceilings with strategic, patchable openings — staged circuit by circuit so the house stays livable. Kitchens, bathrooms, and the most-loaded bedroom circuits usually go first. It's permitted, inspected work, and pairing it with any planned panel replacement means walls open once instead of twice.
In the Puget Sound
Seattle's Craftsman belt — Ballard, Wallingford, Queen Anne, the Central District — and Tacoma's North End are full of homes wired this way between the 1900s and 1940s; finding K&T there is normal, and planning its retirement is routine work.
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Trade: Electrical