Knob-and-tube wiring (K&T) is what was used in Ontario homes from roughly 1900 through the late 1940s, and it is still active in a surprising number of homes in lower Hamilton, Dundas, Ancaster, the older Burlington stock, and the original cabins on Muskoka lakes. If your buyer's inspector or your insurer flagged active K&T, knob-and-tube wiring removal is the conversation - and it is more nuanced than "rip it all out."
What knob-and-tube is
K&T uses individual insulated conductors run through ceramic knobs (on framing surfaces) and ceramic tubes (through framing members), with no shared sheath, no ground conductor, and rubber-and-cloth insulation on the wire itself. The system was code-legal when installed, and a well-installed K&T circuit that has not been disturbed is electrically fine for the loads the original electrician designed it for - lighting and a handful of small appliances.
The problem is not the system as designed. The problems are: (1) the rubber-and-cloth insulation embrittles over a century and crumbles when disturbed, (2) modern household loads (microwaves, A/C, electric vehicles, electric kettles, hair dryers) overload original-spec circuits, (3) DIY modifications stretching back 70 years have stacked taps and extensions onto K&T that were never inspected, and (4) the lack of a ground conductor means modern three-prong appliances cannot be properly grounded.
Why insurers care
Active K&T in occupied homes is correlated with elevated electrical fire risk - not the original work, but the cumulative damage from a century of layered modifications and overloaded circuits. Most Ontario home insurers now either require K&T remediation as a condition of coverage or charge a substantial premium surcharge. The insurance ask is "remediate" - meaning either remove the active K&T or document that all active K&T has been replaced and any remaining K&T in the building is permanently de-energized.
What "knob-and-tube wiring removal" actually means
There are three valid approaches:
- Whole-house rewire. Remove every active K&T circuit and replace with current code-compliant copper NMD90 with proper grounding. This is the cleanest outcome and the most disruptive - drywall work follows. Best for homes where K&T is everywhere.
- Incremental replacement. Identify active K&T circuit-by-circuit, replace each one, leave the dead K&T (visibly disconnected and labelled) in the walls and attic. Best for homes where K&T is localized to certain areas.
- De-energize and replace by exception. Disconnect all K&T at the panel, run new circuits to the rooms it was serving. Document the K&T as permanently de-energized. Best for homes where K&T mostly served the attic and a few rooms.
The right approach depends on what is there and what the homeowner wants. We do an inspection first, document what is active, and quote in writing - no guessing.
How we identify active K&T
Visually: ceramic knobs and tubes are easy to spot in the basement and attic. The harder calls are in the walls - we use a combination of circuit tracing (energize a circuit at the panel and trace where it goes), visual inspection at outlet and switch boxes (K&T conductors look different from NMD90 even at the device landing), and on tight calls, removing a small section of drywall in a closet to confirm.
A common surprise: K&T that was supposed to have been "abandoned" in a previous renovation often turns out to still be live - the previous electrician disconnected the wrong end, or someone tapped onto it years later.
What it costs
Scope varies more than any other category we work on, so the conversation has to start with what you actually have. A small targeted incremental replacement (two or three active K&T circuits in an otherwise modern home) is a very different job from a meaningful partial rewire (most of the second floor, retaining new wiring elsewhere), and both are very different from a whole-house rewire of a Hamilton century home with drywall repair. We walk the house, document what is active K&T versus already-replaced, identify the access points and the drywall repair scope, and quote in writing.
None of those numbers are useful without seeing the property. We charge a flat diagnostic fee for the inspection and apply it to the job if you go ahead.
What you get at the end
- ESA Certificate of Inspection - the document your insurer will ask for.
- Photo documentation of K&T removed, K&T de-energized, and new circuits installed.
- Updated panel legend reflecting the new circuit layout.
- Insurance letter if your insurer asks for a sworn statement from the LEC.
When to call us
If you have K&T in a Hamilton, Dundas, Ancaster, Burlington, or older Muskoka home and your insurer or buyer's inspector is asking, we do this residential electrical work routinely. A whole-house rewire usually pairs with a service upgrade so the new circuits land on a clean panel. Request an inspection and we will document what is there, quote the right approach, and get the ESA inspection done.