Knob-and-Tube Wiring: What It Is, What It Means for You
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.
The part nobody can see later
Most of what decides how this holds up gets covered before the job is over. Once it is closed in, the only record of how it went in is the photos taken while it was still open.
Supervisr's Electrical QA model works from common industry practice and the installation instructions that ship with the materials. It can review electrical installation photos for GFCI and AFCI protection coverage, panel labeling and capacity, branch circuit routing, grounding and bonding integrity, and 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.
For a homeowner, that record is a straightforward way to understand what you paid for. For a contractor, it is the milestone documentation that stands behind a workmanship warranty years later, long after the crew has moved on to the next job.
About Supervisr
Supervisr is an AI quality-assurance platform for residential electrical work. It works from common industry practice and manufacturer installation instructions, and evaluates electrical installation photos for GFCI/AFCI protection, panel labeling, outlet spacing, and grounding details.
Contractors use Supervisr to document quality at each milestone — backing up a workmanship warranty and building a track record of work they can point to. Homeowners end up with a clear record of what went into their home. See how it works at supervisrapp.com.