EZSMART Corporation, ESA/ECRA #7012690 , North York , Ontario
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Power surges can permanently destroy appliances, and they do so far more often than most homeowners realize. A surge severe enough to damage a refrigerator compressor controller, a television mainboard, or a smart thermostat can happen in a fraction of a second — often without any visible sign that anything occurred. Understanding how surges damage appliances, which devices are most at risk, and what protection actually works helps you make informed decisions about your home’s electrical system.
Yes. Power surges destroy appliances in two ways: instantaneous dielectric breakdown that kills a component in microseconds, and cumulative degradation that weakens components over months until they fail under normal load. Both mechanisms are common, and the second one is much harder to detect — an appliance damaged by repeated small surges may appear to work normally right up until it fails completely.
A power surge is a transient voltage increase above the normal 120V (or 240V for large appliances) that your home electrical system delivers. Surges are typically brief — from microseconds to a few milliseconds — but the voltage spike can reach hundreds or even thousands of volts above nominal. The energy content of the spike, not just its peak voltage, determines how much damage it causes.
Surges originate from several sources. Lightning strikes to power lines inject enormous energy into the distribution system and can travel through your home’s wiring to every connected device. Utility switching — when the power company switches between grid segments during routine maintenance or fault recovery — creates voltage transients that travel into homes on the distribution line. Large motors in your home (central air conditioners, refrigerator compressors, well pumps) create switching transients when they start and stop — these internal surges are actually the most frequent source of appliance damage, and they occur dozens of times per day in a typical home.
Modern appliances — including refrigerators, washing machines, dishwashers, HVAC systems, and televisions — contain electronic control boards with semiconductor components: microcontrollers, power supply components, MOSFETs, and integrated circuits. These components are designed to operate at specific voltage levels and have a maximum voltage tolerance (the dielectric withstand voltage of their gate oxides, capacitor dielectrics, and junction regions).
When a surge exceeds this tolerance, the component fails. For MOSFETs and ICs, the gate oxide — a layer measured in nanometres — ruptures. For capacitors, the dielectric breaks down. These failures are often instantaneous and always permanent. A failed control board in a high-efficiency washing machine costs as much as the machine itself to replace; many homeowners are told by technicians that the board “just failed” when in reality it was surge-damaged over months of smaller transients before one larger event finished it.
The most surge-vulnerable appliances are those with sophisticated electronic control systems:
The Electrical Safety Authority (ESA) in Ontario recommends whole-home surge protection installed at the electrical service entrance as the most comprehensive protection for residential electrical systems. A service entrance surge protective device (SPD) — sometimes called a Type 1 or Type 2 SPD — clamps transient voltages before they reach any branch circuit in the home. This protects every connected device, including appliances connected to circuits that are not near an outlet (like a hardwired HVAC system or an electric range).
The Ontario Electrical Safety Code (OESC) and the Canadian Electrical Code (CEC) reference CSA C22.2 No. 269 for the testing and rating of surge protective devices. An SPD installed at the service entrance must be rated for the available fault current at the panel and must be installed by an ESA-licensed electrician. This is not a DIY installation — an improperly installed SPD can fail dangerously under a large surge event.
A surge protector power bar (point-of-use SPD) provides limited protection against surges that enter from the utility side. It uses metal oxide varistors (MOVs) to absorb surge energy, clamping the voltage reaching connected devices. The limitations of point-of-use protectors are significant: they do not protect hardwired appliances, they degrade with each surge event (a MOV that has absorbed several large surges may provide no protection at all while still appearing to function), and they do not protect against internal surges generated by large motors on the same electrical system.
Whole-home surge protection addresses all three limitations. An SPD at the panel intercepts surges from the utility before they branch into individual circuits, and it protects hardwired appliances. The correct approach is layered protection: whole-home SPD at the panel plus point-of-use surge protectors for the most sensitive electronics. See our guide on why power strips catch on fire — MOV-equipped surge protectors are power strips with surge protection, and the same loading and certification rules apply to both.
Coverage varies by policy. Lightning-caused surge damage is covered under most standard homeowner’s policies if it damages a connected appliance. Utility switching surges and internal surges are often not covered, or are covered only under a riders or endorsements specifically for electrical damage. Review your policy’s exclusions and talk to your insurer about adding overland water or electrical surge endorsements if they are not included.
An ESA-licensed electrician can provide documentation that a whole-home SPD was installed to code — some insurers offer premium reductions for homes with documented surge protection. The installation cost of a whole-home SPD is typically several hundred dollars installed, which is far less than replacing a refrigerator, HVAC system, or home theatre setup.
If your home experiences a significant surge event — a nearby lightning strike, a sudden power outage followed by restoration, or appliances that go dead simultaneously — have the following checked before assuming all affected devices can be safely put back in service:
If a breaker fails to reset after a surge event, do not attempt to force it. A breaker that trips due to a surge and cannot be reset may have an internal fault — an ESA-licensed electrician should inspect the panel before power is restored to that circuit. Also see our guide on whether it is safe to charge a phone on a bed — voltage surges reaching bedroom outlets can damage phone charging circuits and battery management systems in the same way they damage larger appliance control boards.
We are called to inspect appliance failures regularly where the homeowner assumes the appliance simply wore out. In a significant number of cases — particularly for control board failures in refrigerators and HVAC systems under ten years old — the damage pattern is consistent with surge degradation: multiple small component failures on the same board, carbon tracking on the PCB surface, or failed MOV components in the appliance’s internal power supply. These are not wear failures. They are surge failures that accumulated over months. The homeowner spent $400 to $800 on a control board replacement when a $300 to $400 whole-home SPD installed years earlier would have prevented the failure entirely. Whole-home surge protection is one of the most cost-effective electrical upgrades available for a home with modern appliances — the math is straightforward once you add up what is at risk.
Want whole-home surge protection installed or need a post-surge inspection? Our ESA-certified electricians serve the GTA. Call us at 416-838-9006 or visit our contact page — we will get back to you the same day.
Electrician Since 2008 Journeyman Electrician Designated Master Electrician at EZSMART Corp
