Knob-and-Tube Wiring: What It Is, What It Means for You
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Your inspection report says "knob-and-tube wiring observed." It's not automatically dangerous. It is automatically an insurance and resale conversation.
What knob-and-tube is
K&T was the standard residential wiring method from the 1880s through the 1940s. Insulated copper wire is run through ceramic knobs (insulators) and through framing on ceramic tubes. The two conductors (hot and neutral) run separately, often with significant space between them.
What it's not
• Inherently more fire-prone than modern wiring, IF the insulation is intact and the wiring hasn't been overloaded or modified
• Always the wiring for the whole house — many homes are partially K&T and partially modern Romex
• Always required to be replaced
What it doesn't do well
• Carry modern loads (kitchens, laundry, HVAC) that didn't exist when it was installed
• Provide a grounding conductor (no third wire)
• Tolerate insulation contact (blown-in attic insulation around K&T overheats; many jurisdictions require its removal where K&T is present)
• Pass modern code if added to or modified
What it means at sale or refinance
Most insurance carriers in the U.S. won't write a homeowner's policy on a home with active K&T without remediation. Some allow partial K&T (attic-only, say). Lenders sometimes flag it. Buyers will negotiate.
What this means for you
If you have K&T, get it assessed by an electrician who deals with it regularly. The answer is rarely "rip it all out tomorrow" — it's a plan to phase it out as you upgrade.
What contractors should know
The plan-to-phase approach is the right pitch. Customers who feel rushed make worse decisions than customers who get a multi-year roadmap.
Before you call anyone out
If you're not sure whether the work was done right, the cheapest first step isn't a contractor callback or a paid third-party inspection — it's a documented second opinion you can refer back to.
Supervisr's Electrical QA model follows industry standards and guidelines set forth by the National Electrical Code (NFPA 70), OSHA (1910 Subpart S / 1926 Subpart K electrical safety), ESFI (safety guidance), and the major electrical-equipment manufacturers. It can review electrical installation photos for GFCI and AFCI protection coverage, panel labeling and capacity, branch circuit routing, grounding and bonding integrity, and code-compliant outlet spacing. Upload photos of panel label accuracy, GFCI/AFCI placement, outlet spacing in kitchens and baths, grounding conductor continuity, breaker sizing vs. wire gauge, and you'll get a documented evaluation back in minutes with citations to the specific standards involved. It's the same checklist a careful inspector uses — applied to your photos, on your timeline.
For homeowners, that documentation is your conversation-starter with the contractor (or, if needed, your insurer or warranty carrier). For contractors, it's the third-party verification that closes the conversation cleanly.
About Supervisr
Supervisr is an AI quality-assurance platform for residential electrical work. It follows industry standards and guidelines set forth by NFPA (National Electrical Code), OSHA, ESFI, and the major electrical-equipment manufacturers, and evaluates electrical installation photos for GFCI/AFCI protection, panel labeling, outlet spacing, and grounding details.
Homeowners use Supervisr to verify a contractor's work without playing inspector themselves. Contractors use Supervisr to document quality at each milestone — protecting against warranty disputes and building a track record of verified work. For more on how Supervisr's QA model follows the published references for Electrical installations, visit supervisrapp.com.