Knob & Tube Rewiring in North York & Toronto

It is an early wiring method used in North American homes from the late 1800s into the middle of the twentieth century. Individual conductors run separately through the structure, supported clear of the timber on ceramic knobs and passing through joists and studs inside ceramic tubes.

The main practical difference from modern wiring is that original installations generally did not include the separate equipment grounding conductor newer systems are expected to have, which is why homes on original circuits usually still have two-prong receptacles.

No. There is no rule that says every length of it must come out simply because it exists. What matters is its condition, what has been done to it over the years, how it has been modified, and what the circuits are being asked to carry now.

What does tend to force the question is a renovation, an insurer, a lack of grounding on circuits you need grounded, or loads the original installation was never designed around. Those are reasons to assess it properly — not a reason to assume the answer in advance.

The usual starting point is an unfinished basement ceiling or an accessible attic, where original wiring is often visible: single conductors held on white ceramic knobs, passing through the timber inside ceramic tubes. Two-prong receptacles throughout a house are another common indicator, though not a conclusive one.

What you can see does not tell you what is concealed. Some homes have had part of the wiring replaced already, and abandoned conductors left in place can look identical to live ones. Confirming what is actually connected and in service is part of the assessment.

Sometimes, yes — particularly where the remaining knob and tube is limited to certain circuits or one area, and earlier work already replaced the rest. It is a legitimate outcome and not a shortcut.

It cannot be promised in advance, though. Whether partial work is appropriate depends on how the existing circuits are arranged, what condition they are in, what is reachable without opening finished work unnecessarily, and what the assessment finds once someone is in the house.

Sometimes. Rewiring replaces cables that run inside the structure, so how much access is needed depends on the house and the routing available. Open basement ceilings, attics, closets and floor cavities often carry a good share of the work.

We plan routes to limit unnecessary access where it is practical, but we will not promise a rewire with no holes or no drywall damage. Drywall patching and painting are not part of the electrical scope unless specifically agreed, so we will tell you where access is likely to be needed and you can plan the making-good accordingly.

Original installations generally did not include the separate equipment grounding conductor expected in modern wiring. That is the reason those circuits usually serve two-prong receptacles.

It also means replacing a two-prong outlet with a three-prong one on such a circuit does not create a ground — it just puts a grounding-type receptacle on a circuit that has none. Where grounded circuits are needed, that is part of what a rewiring scope addresses.

It can, for some properties. Insurance requirements vary by insurer and property. Homeowners should confirm specific requirements directly with their insurance provider.

Some insurers ask about wiring methods when quoting or renewing and treat the answer differently from one another. We cannot tell you what any particular insurer will decide, and we would be wary of any contractor who claims they can. If your insurer has asked for something specific, tell us what it is and we will be straight with you about whether the work would address it.

Rewiring work is generally notifiable — replacing branch circuits, altering the existing installation and work involving the panel are the kinds of job that require it. An initial look at what a house has is not the same thing.

Where notification applies, we file it and coordinate the inspection with the Electrical Safety Authority as part of the job, and we will tell you at the outset whether your work falls into that category.

Not automatically. Rewiring and panel or service upgrades are related decisions but separate ones, and plenty of homes have had the panel replaced at some point while the original branch circuits behind the walls were left alone.

Where substantial new load or a number of new circuits are being added, the available panel and service capacity is reviewed on its own terms, and where the project calls for one a load calculation establishes what the existing service can carry.