The home inspection report said it plainly: “Knob-and-tube wiring present in attic spaces and basement. Recommend evaluation by licensed electrician.” We’d been told about this in advance by our realtor. We thought we understood what we were getting into. We did not fully understand what we were getting into.
This post is the full account of our electrical situation — what we found, what we learned, what it cost, and the decision framework we used to prioritize the work. If you’re buying an old house, this is going to be relevant.
What Knob-and-Tube Actually Is
Knob-and-tube (K&T) wiring was the standard residential electrical system from roughly 1880 through the 1940s. It uses individual hot and neutral conductors — separated and supported by ceramic knobs and tubes — running through the framing of the house. It has no ground wire. The conductors are insulated with rubber and cloth, not plastic.
K&T is not inherently dangerous when it’s in original, undisturbed condition and being used within its designed load. The problems arise from: degraded insulation (the rubber cracks and crumbles over 80+ years), improper modifications made by previous owners over the decades, insulation being blown over K&T in the attic (which traps heat and can cause fires), and overloaded circuits from modern appliances drawing more current than the original wiring was sized for.
What Our Electrician Found
We had two licensed electricians come through for independent evaluations. The assessments were consistent. The good news: the attic K&T was original, intact, and hadn’t been buried under insulation (we’d never had the attic properly insulated, which turned out to have a silver lining). The bad news: the basement K&T showed evidence of repeated amateur modifications — spliced conductors, improper junction connections, and in two places, what appeared to be aluminum wire pigtailed directly to copper.
The panel itself was also a problem. The house had been updated to a 100-amp service panel at some point, but it was a Federal Pacific Stab-Lok — a brand with a documented history of breaker failures that don’t trip properly under overload conditions. Every electrician we talked to said the panel had to go regardless of what we did about the K&T.
The Decision Framework
Full replacement of all K&T wiring in a 1,420 SF house typically runs $8,000–$15,000 depending on accessibility and local labor rates. We got quotes ranging from $9,200 to $13,800. That was not in our first-year budget. We needed a prioritization framework.
We worked with our primary electrician to identify three tiers. Tier 1 (do immediately): replace the Federal Pacific panel, replace all K&T in the basement where modifications had compromised the system, add GFCI protection to all bathrooms and kitchen circuits, and add smoke/CO detectors to current code. Tier 2 (do before insulating attic): replace K&T in attic spaces so we could properly insulate. Tier 3 (do as we renovate rooms): replace K&T circuit by circuit in each room as we gut and renovate, spreading the cost over years of renovation work.
This approach let us address the actual safety risks immediately while deferring the lower-risk original attic K&T to a more financially manageable timeline.
Tier 1 Cost
Panel replacement (Federal Pacific out, 200-amp Square D in): $3,200 including permit and inspection. Basement K&T replacement and proper junction work: $1,850. GFCI protection throughout: $380. Smoke and CO detectors to current code: $290. Total Tier 1: $5,720.
That was painful. It was also not optional. The Federal Pacific panel alone was a genuine fire risk regardless of anything else going on with the wiring.
The Insurance Dimension
One thing that pushed us to accelerate the K&T replacement beyond our original timeline: insurance. When we went to renew our homeowner’s policy in year two, our insurer required documentation that we had a plan to address the remaining K&T or they would non-renew. We ended up completing the attic K&T replacement (Tier 2) in year two partly because of this pressure, at a cost of $2,600.
The remaining K&T — in the walls of rooms we haven’t yet renovated — is being replaced circuit by circuit as we gut each room. The electrician runs new Romex while the walls are open, which is far cheaper than fishing wire through finished walls. We’ve now replaced about 60% of the original K&T this way as a byproduct of our room-by-room renovation.
The Honest Bottom Line
If we had known going in exactly how much the electrical work would cost in total, we probably still would have bought the house. The K&T situation was priced into the purchase — we paid well below market because of the house’s condition. But we would have budgeted differently in year one, and we would have been more aggressive about getting the attic K&T handled before winter rather than letting the insulation delay stretch.
For anyone buying an old house: get an electrician (not just a home inspector) to walk the electrical system before closing. Home inspectors are generalists. Electricians will tell you specifically what they see, what it costs to fix, and what the actual risk level is. That information is worth far more than the $200–400 the evaluation costs.