Wiring & Rewiring in Portland & Southern Maine

Knob-and-tube wiring was the standard method in the U.S. roughly from the 1880s through the 1940s — individual conductors run through ceramic knobs and tubes, with no ground wire and no sheathing binding the wires together. It was well-engineered for its time, and where it's still in good condition and undisturbed, it isn't automatically dangerous.

The problems show up with age and modification: the rubber-and-cloth insulation dries out and cracks over 70-plus years, and decades of homeowners adding insulation on top of it (which knob-and-tube was never designed to have touching it) or splicing into it without a junction box create real fire risk. It's also why many homeowners insurers in Maine now decline to write or renew a policy on a home with active knob-and-tube circuits, or require it be replaced first.

During a copper shortage in the mid-1960s and early 1970s, a lot of homes were wired with aluminum branch-circuit conductors instead of copper. The wire itself carries current fine — the issue is the connections. Aluminum expands and contracts more than copper with heating and cooling, and older devices weren't rated to handle that, so the connection loosens, oxidizes, and heats up over years of use.

The U.S. Consumer Product Safety Commission's own research on this era of wiring found connections on aluminum branch circuits failed at a dramatically higher rate than the same connections on copper — enough that it's treated as its own inspection category, not a footnote.

• Copper pigtailing — the aluminum wire is spliced to a short copper pigtail using a connector actually rated for aluminum-to-copper joints (not a standard wire nut), then the copper pigtail lands on the outlet or switch. This is the accepted repair method and far less invasive than a full rewire.
• Full replacement — for a whole-house knob-and-tube system near the end of its life, or where a remodel already has the walls open, running new copper NM cable throughout is the more permanent fix.
• Device swaps — outlets and switches rated "CO/ALR" are designed to be connected directly to aluminum wire; older devices without that rating are part of why aluminum wiring earned its reputation.

If you're already having us open up a panel or a wall for another reason — a kitchen remodel, a panel upgrade, an addition — it's the cheapest time to deal with either wiring type on that circuit, since the labor to expose it is already being spent. We flag both conditions during any panel or major electrical job rather than waiting for them to become their own emergency.