Is knob-and-tube wiring safe, and does it have to be replaced?

Knob-and-tube is a two-wire wiring method with no equipment ground. The hot and neutral run as separate individual conductors, held away from framing by white ceramic knobs and passed through joists and studs inside ceramic tubes. The air gap around each conductor is part of the design: it's how the system stays cool.

The easiest place to find it is an unfinished basement ceiling or an attic. You're looking for those ceramic pieces and for two conductors running along separate paths rather than together inside one jacket. Cloth-jacketed NM cable, which showed up around 1926, is a different thing and is often confused with it.

Knob-and-tube was prevalent from the 1880s into the 1940s. Installation continued in places later than that, and it can turn up in post-1940s remodels where someone tapped into an existing run. Cloth-jacketed NM appeared around 1926, and modern plastic-jacketed NM took over roughly between 1950 and 1970.

The practical point: build year narrows the odds, it doesn't settle the question. We've found live knob-and-tube in houses nobody expected it in, and found none in houses everybody assumed had it.

Spokane's housing stock is old by west-coast standards. Using Spokane County Assessor data, the City of Spokane reported in 2020 that about 19% of city housing was built before 1940 and roughly 42% before 1970, with the average single-family home around 70 years old.

That's why this question comes up constantly on the South Hill and in Browne's Addition, where a large share of the housing predates the second world war.

No, not on its own. If it hasn't been modified, hasn't been added to, and isn't degraded by water or heat, there is no code requiring its removal. It can stay.

New Romex and existing knob-and-tube can also coexist. Running new circuits in a house does not oblige you to tear out what's already there, as long as what's already there is intact and untouched.

Aaron's own position, for what it's worth: if it were his house, he'd replace it. That's an opinion from someone who has opened a lot of these walls, not a code requirement, and we'll still scope your house on what's actually in it.

For most homeowners this decision gets made by an insurance carrier rather than by safety or by code. Some carriers will not write a policy on a house with knob-and-tube at all. Others will, and you can find them; it takes calling around rather than accepting the first no.

What we can't tell you is how the premiums compare. We don't know, and we're not going to guess at it. That's a question for a broker who writes in this market.

If you've received a letter, don't guess at what will satisfy them. Bring it to us with the specific language, and we'll look at what's actually in your house and what would address it.

The wiring isn't usually the difficult part. The walls are. Houses of this age are lath and plaster, and you can't cut it cleanly. It chips, it cracks beyond the cut, and it behaves more like concrete than like drywall.

That's the honest reason South Hill and Browne's Addition rewires cost what they do. Most of the planning on those jobs is about finding paths that don't turn into plaster repair, because the patching is a bigger job than the wiring.

Not always, and not always at once. Plenty of older Spokane homes have knob-and-tube that was abandoned in place decades ago when someone rewired part of the house. Abandoned, de-energized conductors sitting in a wall are not the same problem as live ones.

A realistic scope often looks like: identify what's still energized, de-energize and remove what can be removed, and replace the live circuits, sometimes in phases, prioritizing kitchens, bathrooms, and anything buried in insulation. Sometimes the assessment does come back as a full rewire, and we'll say so plainly when it does.

Replacement means running new grounded cable to the devices and fixtures on the affected circuits, adding boxes where splices were made outside of them, and terminating everything properly at the panel. Older homes frequently need panel work at the same time: a two-wire system usually came with a service sized for a two-wire era, and grounding and bonding often need correcting.

Full detail on scope, access, and phasing is on our whole-home rewiring page, and the service side is covered on the panel upgrade page. Cost depends on access, how much of the house is finished, how many circuits are live, and whether the service needs to change. We scope it after seeing it, not over the phone.