EZSMART Corporation, ESA/ECRA #7012690 , North York , Ontario
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Power strips are among the most commonly misused electrical devices in Canadian homes. A strip that appears to work fine for years can overheat and ignite without visible warning — and the fires they cause tend to start inside walls or behind furniture where they cannot be quickly detected.
Power strips catch fire for four main reasons: they are overloaded beyond their rated current capacity, they are connected in a chain with other strips or extension cords, they have internal wiring faults from age or damage, or they are uncertified products with substandard components. Understanding each failure mode helps you identify which strips in your home are actually at risk.
Every power strip has a maximum current rating, typically 15 amperes at 120V (1,800 watts). This rating applies to the total draw of everything plugged into it — not the rating of any individual device. A strip with a space heater (1,500W), a laptop charger (65W), and a phone charger (18W) is already near its limit. Add a second heater, a television, or a gaming console and the strip is drawing more current than its internal wiring can safely carry. The wiring heats up, the insulation degrades, and if the strip lacks adequate thermal protection, it ignites.
The current rating of a power strip’s breaker or fuse does not protect the strip’s internal wiring — it protects the circuit the strip is plugged into. A strip rated at 15A plugged into a 15A outlet will not trip the outlet’s breaker when it overheats internally, because the breaker on the wall only trips when the entire circuit is overloaded. The fire risk lives in the strip itself, not in the circuit breaker.
Plugging one power strip into another — commonly called daisy-chaining — is prohibited by the Ontario Electrical Safety Code (OESC) and is explicitly listed as a fire hazard by the Electrical Safety Authority (ESA). When two strips are chained, the total current drawn by all devices connected to the second strip must travel through the cord of the first strip. A first strip rated for 15A is now carrying 15A of devices plus the standby draw of the second strip’s internal components — all through wiring rated for a specific current at a specific ambient temperature.
The first strip’s cord, which connects it to the wall, is typically 16 AWG or 14 AWG — rated for 13A or 15A respectively in free air. Under load, packed against a baseboard or bundled with other cords, its effective current capacity is lower. See our guide on the dangers of daisy-chaining power strips for a detailed breakdown of why chained strips fail catastrophically while appearing to work normally for months before the failure.
Power strips are consumer products with a finite service life. Internal connection points loosen over time — the spring contacts that grip plug blades wear down, creating higher resistance at the connection, which creates heat under load. A strip that has been used for five or more years in a fixed location should be inspected for signs of discolouration, melted plastic around outlets, or visible heat marks on the cord or casing.
Physical damage accelerates this process. A cord that has been bent sharply at the point it enters the strip housing, run under furniture, or partially crushed develops internal strand breaks. These breaks create high-resistance joints — concentrated heat sources — at exactly the point where the cord enters an enclosed plastic housing with no ventilation. See our guide on what causes wiring insulation to become brittle for the failure mechanism that applies to power strip cords as well as fixed wiring.
The Canadian market requires power strips to carry CSA (Canadian Standards Association) or UL certification for use in Canada. Uncertified strips — commonly purchased from discount or online marketplaces — may have undersized internal wiring, inadequate surge suppressor components (MOVs that fail in a sustained arc rather than a benign failure), and thermal cutoffs that activate too late or not at all. These strips can fail at current levels well below their stated rating.
Always verify CSA or cUL markings on any power strip before use. The certification mark appears on the label, not just on the packaging — counterfeit products often print the marking on the box but not on the device itself. If a strip does not have a verifiable certification mark on the device, do not use it.
The Electrical Safety Authority identifies power strip misuse — specifically overloading and daisy-chaining — as one of the most common contributors to residential electrical fires in Ontario. The ESA recommends:
If you find yourself using a power strip in a fixed location every day because there are not enough outlets on the wall, the correct solution is to have a licensed electrician add outlets where they are needed. See our guide on whether you can plug a surge protector into an extension cord — the same loading and certification logic applies there.
A surge protector is a power strip with metal oxide varistors (MOVs) that absorb transient voltage spikes. The surge protection function does not change the thermal risk from overloading. A surge protector overloaded with high-draw devices will overheat just as readily as a basic power bar — the MOVs protect your electronics from voltage spikes, not your wiring from excess current. Additionally, MOVs degrade with each surge event they absorb; a surge protector that has experienced multiple large surges may no longer provide surge protection even though it still functions as a power strip. Can power surges destroy appliances? See our companion post on whether power surges can destroy appliances for what surges actually do to connected equipment.
The power strip fires we are called to investigate after the fact almost always follow one of two patterns: a strip behind or under a piece of furniture that was loaded with multiple devices for years without anyone noticing heat or smell, or a strip used to power a space heater in addition to other devices on a temporary basis that became permanent. In both cases, the failure is predictable — the strip was loaded beyond its rating for long enough that internal connections degraded to the point of arcing. The solution is not a better-rated power strip. It is to add the right number of outlets in the right locations so power strips are used temporarily and for low-draw devices only. If you are using more than three or four power strips in your home on a regular basis, have a licensed electrician assess your outlet layout — the cost is minimal compared to what a power strip fire costs.
Need more outlets added to reduce your reliance on power strips? 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
