EZSMART Corporation, ESA/ECRA #7012690 , North York , Ontario
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Open a device box in a Toronto or GTA home and find melted, discoloured plastic around a wire nut or a device terminal, and you have found a genuine near-miss. Connections do not melt from normal use — something specific went wrong at that exact point. This guide covers why melting happens almost exclusively at connections rather than mid-cable, and what fixes it for good.
Wires melt at a connection because that is where resistance concentrates when a termination is loose, corroded, undersized, or improperly made. A solid run of copper conductor has almost no resistance and generates almost no heat under normal load. A loose wire nut, a backstabbed outlet with a weak spring contact, or a corroded aluminum-to-copper junction has real resistance right at that single point — and resistance under current load generates heat exactly where it is, which is why the melting is always localized to the connection and rarely spreads evenly along the cable.
Electrical heat generation follows a simple relationship: more resistance at a fixed current means more heat. A tight, clean copper-to-copper connection has near-zero resistance. Every gap, every bit of oxidation, every strand that is not fully seated against its neighbour adds resistance. That resistance turns electrical energy into heat right at the point of contact — not evenly distributed like it would be along a long run of wire, but concentrated in a few millimetres of connection. Enough heat over enough cycles softens and eventually chars the plastic wire nut or device body around it.
A continuous run of properly sized copper cable has consistent, low resistance along its entire length — there is no single weak point for heat to concentrate. A connection, by contrast, is inherently a mechanical joint: two or more separate conductors relying on contact pressure (a screw, a spring, a crimp, a twisted wire nut) to carry current across a boundary. That boundary is the only place resistance can meaningfully vary from perfect, which is why virtually every wire-melting incident traces back to a splice, a terminal, or a connector — never a clean, undisturbed length of cable in between.
Any of these is the same failure in progress, just earlier in the timeline. See why do my outlets smell like melting plastic.
Every time we find one melted connection in a GTA home, we check every other backstabbed device on that same circuit and usually the whole panel’s worth of similar-vintage devices, because the installer who backstabbed one outlet backstabbed all of them. A single melted connection is rarely a one-off — it is the first one to fail out of a batch that were all installed the same marginal way. Treat it as a signal to audit the whole circuit, not just replace the one device.
The device swap itself can be homeowner-friendly, but the wire underneath often needs inspection and trimming back to sound copper — have a licensed contractor check it first.
Not automatically, but it strongly warrants checking every similar device on that circuit for the same installation pattern.
If the breaker is off, current stops flowing and heat generation stops. The risk resumes if power is restored without repair.
It is code-legal on lighter loads but has a well-documented failure rate over time compared to screw terminals, which is why pros default to screw terminals.
Coverage depends on the specific policy and whether the underlying wiring work was permitted and up to code.
Found a melted connection in your Toronto or GTA home? Kill the breaker and call ezsmart at 416-838-9006 or use our contact page. An ESA-licensed electrician will repair it and check the rest of the circuit.
Electrician Since 2008 Journeyman Electrician Designated Master Electrician at EZSMART Corp
