Open a kitchen wall in a Portland house built before 1945 and there’s a fair chance you’ll find wiring older than the refrigerator. Two single wires, held apart, running through porcelain knobs and tubes. It still works. That’s the problem: it works well enough that nobody replaced it, and the kitchen is the one room where 1920s wiring meets the electrical load of today.
This post covers what knob-and-tube is, why a kitchen remodel is where it comes up, what the permit and inspection actually mean for it, and how it changes your quote. Where the rules leave room for judgment, we say so. Often the honest answer is that the inspector decides on site.
What knob-and-tube wiring is
Knob-and-tube was the standard way to wire American houses until about the 1940s. Each circuit uses two separate insulated conductors, one hot and one neutral, held in open air by porcelain knobs along the framing and threaded through porcelain tubes where they cross a joist or stud. There is no third, grounding wire. The air around the conductors was part of the design, because it let the wire shed heat.
Portland has a lot of it. The bungalow building boom that shaped Sellwood, Alberta, Woodstock, Ladd’s Addition and most of inner SE and NE put up houses between roughly 1905 and 1940, and many were wired this way. Very few still are, entirely. After a century, most houses have been partly updated: a newer panel in the basement, a modern circuit for a bathroom, outlets added in the 1960s. What you end up with is a mix, and the mix is what needs reading carefully.
Is it dangerous?
Not by itself. Knob-and-tube that is intact, uncovered and carrying the load it was designed for isn’t automatically a hazard, and plenty of it has run for a hundred years. The trouble comes from what has been done to it since:
- Aged insulation. Cloth and rubber coverings dry out, crack and flake, especially near boxes and fixtures where heat builds.
- Oversized protection. Fuses or breakers sized up to stop nuisance blowing, so a wire meant for 15 amps sits behind something larger.
- Old splices. Modern cable tied into old wire years ago, inside a wall, by someone in a hurry.
- Insulation over the wire. It traps heat the original design relied on air to carry away.
- No equipment ground. Modern three-prong appliances are built to use one.
Insurance is a separate question. Some insurers ask about old wiring, price it, or want an electrician’s report. Policies differ, so ask yours.
Why the kitchen is where it comes up
A bedroom circuit in 1926 might have run a lamp and a clock. A kitchen now runs a refrigerator, dishwasher, disposal, microwave, hood fan, coffee maker and toaster, often together.
Current code is written around that load. Oregon adopts the National Electrical Code with its own amendments as the Oregon Electrical Specialty Code. In a kitchen that means at least two 20-amp circuits for the countertop outlets, outlets spaced so no point along the counter is more than 24 inches from one, GFCI protection at the counter, and arc-fault protection on kitchen circuits. Dishwashers, disposals and microwaves normally get circuits of their own.
A circuit installed for a ceiling light and two outlets can’t be the source for any of that. So in a remodel the question usually isn’t whether the old wiring is “bad.” It’s whether it can carry the new kitchen, and for the new circuits the answer is no. The kitchen gets new wiring. What’s left to decide is what happens to the old circuits that used to serve the room, and to anything they also feed elsewhere in the house. A good layout plans for this up front, which is why electrical sits inside our kitchen design process and not after it.
What the permit and inspection actually mean
Two things are true at once, and mixing them up causes most of the confusion.
In Portland, an electrical permit has to be obtained before work begins that alters or adds permanent wiring, and the wiring has to be installed in accordance with the electrical code (Portland City Code, Title 26). A kitchen remodel that adds circuits, moves outlets or changes lighting is that kind of work. Permitted electrical work is inspected, and new work has to meet the code in force. Oregon’s adopted electrical code page lists the current edition.
It doesn’t say that pulling a permit means the whole house must be rewired. Wiring you don’t touch, in rooms you aren’t remodeling, isn’t generally re-inspected. What the inspector sees is the work you did and the existing wiring it connects to or exposes.
That second part is where judgment comes in. Say the wall behind the sink is open for new plumbing and a knob-and-tube circuit runs through it. The inspector can look at that circuit. An inspector who finds old wiring that is spliced, overloaded or tied into new work can require it to be dealt with. In our experience, when a wall is open and knob-and-tube is feeding the room, that circuit ends up replaced.
That is common practice, not a blanket rule, and what an inspector requires on your house is decided at your inspection. We tell you that before demo, not after. Our permits guide covers who reviews what and how long it takes.
Five things we often find behind pre-war kitchen walls
Not every house has all of these. Most have at least one.
Modern cable spliced into old wire inside a wall, then plastered over. The splice is usually the weak point, not the old wire.
A fuse or breaker rated well above what the wire was made for.
Kitchen outlets on the same circuit as an upstairs bedroom and the porch light. Flip one breaker and half the house goes quiet, and nobody knows why.
Cloth covering that flakes off when touched.
Blown-in insulation added in an exterior wall decades later, over live conductors.
When we open a wall and find any of these, we stop, photograph it, show you, and get your written approval before the plan changes. You can see how that works in our process guide.
What gets replaced and what can stay
This is how it typically goes. Your electrician and your inspector make the final call on your house.
| Situation | Typical outcome | Why |
|---|---|---|
| New kitchen circuits (counter outlets, dishwasher, disposal, microwave, hood) | New wiring and breakers | Code requires them, and old circuits can’t carry the load or provide a ground |
| Old circuit that fed the kitchen, now in an open wall | Usually replaced or removed in the work area | Exposed, with a changed load, and likely to be flagged |
| Knob-and-tube in a room you aren’t touching, in good shape, uncovered | Often can stay for now | Not altered, but assess it before adding load or insulation |
| Old wire spliced to new cable inside the wall you’re opening | Splice and old run usually redone | Concealed splices are a weak point |
| Knob-and-tube covered by insulation | Needs an electrician’s review, often replaced | The NEC doesn’t allow concealed knob-and-tube in insulated hollow spaces |
| Undersized panel or fuse box | Often upgraded with the remodel | The new kitchen needs the capacity |
How to check without opening anything
You can learn a lot without touching a wall or a panel. Please don’t open either yourself.
- Basement or attic: look along the joists for small white porcelain knobs with wire running between them.
- Outlets: two-slot outlets with no ground hole are a clue that older wiring is behind them. They aren’t proof, because some were replaced and some were never rewired.
- The panel: an old fuse box, or a panel that looks too small for the house, usually means the service wasn’t updated with the rest.
A licensed electrician can confirm what’s in the walls. That’s what our walkthrough is for.
How it changes your quote and your schedule
Scope depends on three things: how much of the circuit run is old, how reachable it is (an open wall versus fishing new wire through finished plaster), and what the panel can supply. None of that can be priced from a phone call.
So an honest quote for an older Portland kitchen has an electrical line, and a contingency stated in dollars for what’s behind the walls. If a quote on a 1920s house doesn’t mention electrical at all, ask why. The scope may not be complete, and the gap tends to come back as a change order after demo, when you have the least leverage. Our cost guide explains how we build the number, and what hidden costs blow up a Portland kitchen budget lists the other usual surprises.
On the schedule, the electrical rough-in has to be inspected before walls close. That adds a step, and the timing depends on the city’s review queue. The timeline guide shows where it sits, and how to survive a kitchen remodel covers living through it.
Questions to ask any contractor about old wiring
- Will you open the panel and look for knob-and-tube at the walkthrough, before quoting?
- Is there a separate electrical line in the quote, and what’s in it?
- What happens if you find old wiring I didn’t know about, and who approves the change?
- Who pulls the electrical permit, and who does the work?
- Will you put the electrician’s findings in writing?
More on comparing contractors in how to hire a kitchen contractor in Portland.
Where this comes up most
Knob-and-tube turns up most often in the pre-1945 housing of inner SE and NE. We see the conditions described here in Sellwood-Moreland, Alberta Arts District, Ladd’s Addition, Woodstock and Multnomah Village, and in the older bungalows of North Portland. If you’re opening a wall as part of an open concept remodel, the wiring in that wall is part of the same conversation as the structure.
Frequently Asked Questions
Do I have to replace all the knob-and-tube in my house if I remodel the kitchen?
No. The work follows the area you’re remodeling and what the inspector requires there. We still recommend having the whole house looked at, because circuits are shared between rooms and the panel serves all of them.
Is knob-and-tube illegal in Oregon?
Existing installations aren’t automatically illegal. New knob-and-tube isn’t how houses are wired now, and the code limits it to extensions of existing installations or special permission. How the code treats existing wiring that is covered by insulation or altered by new work is where it gets specific, so confirm with your electrician and Portland’s permitting office.
Can I change the cabinets and counters and leave the wiring alone?
If you don’t add, move or alter any wiring, you may not need an electrical permit. New counters usually mean new outlets or new lighting, though, and that is permitted work. Check with the city before assuming.
Will old wiring affect my homeowner’s insurance?
It can. Some insurers ask about it, price it, or want an electrician’s report. Ask your insurer directly and keep any report you’re given.
Does the electrical work add time to the project?
It adds an inspection before walls close, and the timing depends on the city’s review queue. It’s easier to schedule when it’s in the plan from the start than when it’s found mid-demo.
Not sure what’s behind your kitchen wall?
That’s what the walkthrough is for. At Rainwood Kitchen Craft Co, we look at the panel, the outlets and what’s visible in the basement or attic before we write a number, so the quote reflects the house and not a guess. Call (971) 535-8286 or send the form below.