Rewiring
Knob and Tube and Aluminium Rewiring
Two wiring types insurers will not write. One has an accepted middle path that costs a fraction of a rewire. The other does not.
Two wiring systems get Ontario houses declined at renewal, and they come from opposite ends of the last century.
Knob and tube is pre-1950. Aluminium branch wiring is roughly 1965 to 1978. Neither is unsafe in the abstract. Both are treated as unsafe by underwriters — which, if you are the one holding the policy, amounts to exactly the same thing.
Knob and tube
It is an open-air system. The conductors run separately through porcelain knobs and tubes, and they rely on the air around them to shed heat.
Which works beautifully right up until somebody insulates the attic. Then the wiring is buried in the one thing it was designed not to be buried in. A great deal of the pre-war housing around here has been insulated once or twice since, usually for an energy rebate, decades after the wiring went in and without anybody connecting the two decisions.
It also has no equipment grounding conductor. That is why every outlet in a knob-and-tube house has two prongs, and why the three-prong adaptors people fit are genuinely worse than the problem they solve — they present a grounded receptacle to an appliance that has nothing grounded behind it.
There is no middle path on this one
No connector, no treatment and no partial measure makes knob and tube acceptable to an underwriter while leaving it in place. The circuits get replaced. We would rather say that plainly than sell you something in between.
What can be staged is the order. Panel and service first, then the heaviest circuits, then the rest, with one notification covering the whole scope so the eventual inspection signs off a finished job instead of three partial ones. A knob and tube rewire of an occupied house rarely happens in a single visit, and nobody should pretend otherwise.
Aluminium is a different animal
Aluminium is a perfectly good conductor. The failure is entirely at the terminations.
- It expands and contracts more than copper, so a connection worked by daily heating cycles loosens off.
- It creeps under a screw — slowly deforms, and the contact pressure drops away.
- It oxidises into a resistive layer, where copper oxide stays reasonably conductive.
Every one of those concentrates heat at the connection rather than in the wire. Which is why aluminium wiring problems turn up at outlets, switches and panel lugs, and effectively never in the middle of a run.
And here the middle path does exist
Insurers will frequently accept properly remediated terminations — approved connectors at every device, junction and panel lug, done throughout — instead of a full rewire. It costs a fraction of one.
Whether yours will accept it differs between insurers, so ask before you book anything at all. That one phone call is worth more to you than any quote on this page.
Talk to a Midland electrical contractor
Tell us three things: the town, roughly when the building went up, and what the panel looks like — fuses or breakers, and the number on the main. That is usually enough to say whether you are looking at an afternoon, a scheduled job, or a conversation with your distributor first. Often enough to price it, too, without anybody driving anywhere.