Knob and Tube Wiring:
What You Need to Know
It powered homes for 60 years. It's still in the walls of thousands of houses across Clark County. And it comes with real limitations you should understand.
Knob and tube wiring was the standard method of wiring a house from the 1880s through the early 1940s. If you own a home in downtown Vancouver, the Hough neighborhood, Carter Park, or any of the older areas near the Columbia River, there's a decent chance your home still has some K&T in the walls or attic.
Ryan Newman, owner of Newman Electric in Vancouver, WA, works on homes with knob and tube wiring regularly. "Most people find out they have it when they buy the house and the inspector flags it, or when they try to add insulation and the insulation company won't touch it. Those are usually the two triggers."
What knob and tube wiring actually looks like
Knob and tube gets its name from the white ceramic knobs and tubes that route the wires through your home's framing. The knobs are nailed to joists and studs to support the wire. The tubes are ceramic sleeves that protect the wire where it passes through a stud or joist.
Unlike modern wiring, which bundles the hot and neutral wires together inside a cable sheath, K&T runs the hot and neutral as separate wires spaced several inches apart. This air gap was the original heat dissipation method. The insulation on the wires themselves is rubber or cloth, not the PVC used on modern wiring.
There's no ground wire. Every circuit in a K&T system is a 2-wire ungrounded circuit. That means no 3-prong outlets, no equipment grounding, and no GFCI protection unless it's been added after the fact.
Where the problems come from
K&T wiring that has been left completely alone, in its original condition, with no insulation blown over it, is actually not terrible. It was designed to work in open air, and it does. The problems come from three sources:
Insulation covering the wires
K&T was designed to dissipate heat through open air. When blown-in insulation (cellulose, fiberglass, or foam) buries the wires, that heat has nowhere to go. The wire temperature rises, the old rubber insulation breaks down faster, and the fire risk goes up significantly. This is the single biggest danger with K&T wiring in the Vancouver WA area, because many homeowners added insulation to their attics without knowing K&T was up there.
Deteriorated wire insulation
The rubber and cloth insulation on K&T wires has a lifespan. After 80+ years, it becomes brittle, cracks, and falls off. Bare wire in an attic full of insulation or near wood framing is a short circuit and a fire waiting to happen. You can check this by looking at exposed K&T in your attic or basement. If the insulation is crumbly or missing in spots, it's time to act.
Improper modifications by previous owners
This is the one Ryan's crew sees constantly. Somebody spliced modern Romex onto the old K&T using wire nuts and electrical tape 30 years ago. Or they tapped into a K&T circuit to add outlets in a bedroom. These splices are rarely done correctly, rarely in a proper junction box, and rarely inspected. Every improper splice is a potential failure point.
"A great experience. Ryan came over, diagnosed the problem, and gave me two realistic solutions with honest pros and cons. When Chris and Roman came to do the work, they were fast, polite, and respectful, offering to take their shoes off and being very mindful of their language around my 3 y/o. They showed me how to adjust the settings on the new electrical fixtures and patiently answered my questions, and did a great job cleaning up."
Laurie Hopkins, Google Review
The insurance problem
Insurance is usually the thing that forces the issue. Many standard carriers in Washington won't write a homeowners policy on a house with active knob and tube wiring. Others will, but with higher premiums and an inspection requirement.
If you're buying a home with K&T, your lender's required insurance may be difficult to obtain. If you already own the home, you might get a non-renewal notice from your current carrier when they find out about the wiring during a claim or review.
Getting the K&T removed and replaced with modern wiring usually resolves the insurance issue completely. Newman Electric provides detailed documentation of the work for your insurer. Ryan has seen this process enough times to know what the underwriters are looking for.
What you can do about knob and tube wiring
The options for K&T are more limited than for aluminum wiring. There's no connector-based fix. Either you live with it (and accept the limitations), or you replace it.
Full rewire (recommended)
Remove all K&T circuits and replace them with modern copper wiring, grounded circuits, AFCI protection, and a new panel if needed. This gives you a home that meets current code, accepts 3-prong outlets, and satisfies every insurance company. Cost is $8,000 to $20,000+ depending on home size. Homes with accessible attics and basements cost less because the wiring routes are easier to reach.
Partial rewire (targeted)
Replace K&T only in the areas where insulation is planned, where circuits have been modified, or where the wire insulation is damaged. Leave undamaged, uninsulated K&T circuits in place. This is a budget compromise that addresses the worst hazards. It may or may not satisfy your insurance company, so check first.
Inspection and monitoring
If your K&T is in original condition, unmodified, with no insulation covering it, and your insurance is fine with it, you can have an electrician inspect the system and confirm its condition. Newman Electric can check all visible connections, test circuits, and document the current state. Schedule follow-up inspections every few years to catch deterioration early.
Planning to insulate your attic?
If you have knob and tube wiring in the attic and you want to add insulation, the K&T must be dealt with first. Washington State energy code and most insulation contractors will not allow blown-in insulation over active K&T wiring. The wires either need to be replaced in the insulation zone, or the circuits need to be decommissioned so the old wires are no longer carrying current.
Newman Electric often coordinates with insulation companies on projects like this. Ryan's crew handles the electrical side, the insulation crew follows, and the homeowner ends up with a warm, safe attic. If you're planning insulation work, have the electrical evaluated first so you know the full scope and budget.
Frequently Asked Questions
Is knob and tube wiring safe?
In its original, undamaged, uninsulated condition, K&T is not inherently unsafe. The risks come from deteriorated insulation, improper modifications, and blown-in insulation covering the wires. If any of those conditions exist, you should have it evaluated by a licensed electrician. Newman Electric inspects K&T systems across the Vancouver WA area.
Can I get homeowners insurance with knob and tube?
Many standard carriers in Washington won't insure homes with active K&T. Some specialty insurers will, but usually at higher premiums and with an inspection requirement. Replacing the wiring eliminates the insurance issue entirely. Newman Electric provides documentation that insurers accept.
How much does it cost to replace knob and tube wiring?
A full K&T replacement for a 1,200 to 2,000 square foot home in the Vancouver WA area costs $8,000 to $20,000+. The price depends on the number of circuits, wall access, and whether the attic and basement are open. Homes with good attic and basement access are on the lower end. Newman Electric provides free on-site estimates.
Does knob and tube wiring have to be replaced?
Not by code, unless you're modifying the circuits. But insurance requirements, the inability to add attic insulation over active K&T, and the limitations of ungrounded circuits make replacement a practical necessity for most homeowners. It also removes a major objection if you ever sell the house.
Can I add insulation to my attic if I have K&T wiring?
Not over active K&T wiring. Blown-in insulation traps heat around the wires and creates a fire hazard. The K&T circuits in the insulation zone must be replaced or decommissioned first. Newman Electric coordinates with insulation contractors on these projects regularly.
Related Services
Knob & Tube Replacement
Full service page with pricing, process, and insurance info
Whole House Rewiring
Complete copper rewire for homes with any outdated wiring
Electrical Panel Upgrade
New panel is often needed when replacing K&T circuits
Electrical Safety Inspection
Evaluate the condition of your K&T wiring
Aluminum Wiring Replacement
Another common legacy wiring issue in older homes
Remodel Electrician
Replace K&T during your remodel when walls are already open
Need your knob and tube wiring evaluated?
Newman Electric inspects and replaces knob and tube wiring across Vancouver WA, Clark County, and Cowlitz County. Ryan will look at what you have, tell you the condition, and give you honest options. No charge for the estimate.