What are the odds of a house fire from leaving a charger plugged into the wall?
Evidence quality 4.38/5
Eight-dimension review score against the quality rubric . Each dimension scored 1–5.
- D1 Source grounding
- 3/5
- D2 Source authority
- 5/5
- D3 Arithmetic
- 4/5
- D4 Uncertainty
- 4/5
- D5 Scope
- 4/5
- D6 Prose
- 5/5
- D7 Perception honesty
- 5/5
- D8 Caveat completeness
- 5/5
Lifetime probability · lifetime, US adult
1 in 200,000
0.0005% lifetime chance
Most people overestimate this.
range 1 in 10,000,000 to 1 in 10,000
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≈ As likely as
Perceived
"Unplug your charger when you're not using it" is one of those safety mantras that circulates without a denominator. Fire services repeat it as general precaution, parents pass it to children, and it carries the implicit weight of house-fire statistics that lump together chargers, extension cords, lithium-ion batteries, and counterfeit equipment into a single "electrical fire" bucket. Many people assume a phone charger sitting idle in a socket is slowly overheating, one forgotten night away from burning the house down.
Rough estimate: ~1-5% lifetime chance of a fire from a plugged-in charger
Source: editorial intuition, not polled
Actual
~0 documented fires from certified chargers left plugged in with no device attached
certified (UL/CE) phone and laptop chargers plugged into wall sockets without a device, US/UK
Show derivation
No published fire investigation report, NFPA dataset, or CPSC incident database documents a fire caused by a certified, undamaged phone or laptop charger plugged into a wall socket with no device attached. A no-load charger draws 0.01-0.5 W (typically ~0.1 W for a phone charger), generating negligible heat. Dr. Glen Farivar (University of Melbourne) confirms that modern chargers enter sleep mode with sub-1W draw when no device is connected. The risk is not literally zero -- a manufacturing defect, voltage surge, or degraded component could theoretically cause ignition -- but it is below the threshold of epidemiological detection. We assign a nominal 1-in-10-million annual probability to represent "too rare to measure but not physically impossible." Over 40 years: 1-(1-0.0000001)^40 ≈ 0.000004 or ~0.0005%. The real charger fire risk resides in active charging of lithium-ion batteries (especially e-bikes, power banks) and in counterfeit/ uncertified equipment: 98-99% of tested counterfeits fail basic safety tests. NFPA reports ~1,500 battery-caused home fires per year, virtually all involving active charging or defective products.
Caveats: The "effectively zero" risk assessment applies specifically to certified, undama…
The "effectively zero" risk assessment applies specifically to certified, undamaged, modern chargers with no device attached. The risk profile changes entirely when a device is actively charging, when the charger is counterfeit, or when lithium-ion batteries are involved. NFPA and CPSC do not track "idle certified charger" as a fire cause category, making it impossible to prove a true zero -- only that the rate is too low to appear in any published dataset. Fire service advice to unplug chargers when not in use is precautionary and reasonable (it eliminates even the theoretical risk), but it is often interpreted as implying a much higher risk than the evidence supports. The distinction between certified and counterfeit chargers is load-bearing: a user who heeds the "unplug" advice but buys cheap uncertified chargers has inverted their actual risk profile.
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No published fire investigation in the NFPA, CPSC, or London Fire Brigade datasets documents a house fire caused by a certified, undamaged charger plugged into a wall with no device attached. A phone charger in no-load mode draws about 0.1 watts — roughly the energy output of a single LED indicator light. At that power level, it generates less heat than a nightlight and is physically incapable of igniting surrounding materials under normal conditions. The lifetime probability of a fire from this specific scenario rounds to effectively zero.
The fear is not baseless; it is misattributed. NFPA reports about 1,500 battery-caused home fires per year in the US, but virtually all involve lithium-ion batteries actively charging or failing — e-bikes, power banks, vapes, and hoverboards, not idle wall warts. The other major contributor is counterfeit equipment: Electrical Safety First tested 50 fake iPhone chargers and 98% failed basic safety checks. UL found a 99% failure rate across 400 counterfeit Apple chargers. The fire risk lives in the quality of the charger and in the battery being charged, not in the act of leaving a plug in a socket.
The practical irony is that the “unplug your charger” advice, while harmless, can create a false sense of security. A household that religiously unplugs certified chargers but charges an e-bike with a cheap third-party adapter has exactly inverted its real risk profile. The London Fire Brigade attended 206 e-bike and e-scooter fires in 2025 alone, nearly all during active charging. If the goal is fire prevention, the evidence points to buying certified chargers and never charging lithium-ion devices unattended — not to worrying about the wall wart forgotten behind the sofa.
Claim ledger
Every number below is what each source reported, with the verbatim quote we relied on and how we arrived at our figure. Click any link to verify directly.
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[1] National Fire Protection Association (NFPA) — Home Fires Caused by Electrical Distribution and Lighting Equipment
Home Fires Caused by Electrical Distribution and Lighting EquipmentSee all 2 Likelier entries citing this source →
- Statistic
~30,740 home electrical fires per year in the US (2016-2020), representing ~8-9% of all home fires; ~1,500 battery-caused home fires per year (2014-2018)- Excerpt
“"An estimated 30,740 home structure fires per year were caused by electrical distribution and lighting equipment from 2016 to 2020, resulting in 390 civilian deaths, 1,090 injuries, and $1.4 billion in direct property damage annually." ”
- Source data from
- 2023-01-01
- Accessed
- 2026-04-24 · archived copy
- Calculation
- NFPA's electrical fire data bundles chargers into broader categories (electrical distribution equipment, batteries). There is no standalone "idle charger" fire category because such incidents are too rare or nonexistent to track. The ~1,500 battery-caused fires/year involve active charging or device failures. Cords and plugs cause ~1% of home fires but 6% of fire fatalities, with extension cords as the primary culprit -- not idle wall-wart chargers.
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[2] Electrical Safety First (UK charity) — 98% of fake iPhone chargers fail safety tests
98% of fake iPhone chargers fail safety tests- Statistic
98% of 50 counterfeit iPhone chargers tested failed basic safety checks; genuine chargers contain 60+ components vs ~25 in counterfeits- Excerpt
“"Ninety-eight percent of 50 fake or lookalike iPhone chargers purchased in the UK failed at least one basic safety test. Almost half failed the electric strength test, putting consumers at risk of lethal electric shock. A genuine Apple charger contains over 60 components; counterfeits averaged just 25." ”
- Source data from
- 2017-12-01
- Accessed
- 2026-04-24 · archived copy
- Calculation
- This study establishes the critical distinction between certified and counterfeit chargers. A genuine UL/CE-listed charger has overcurrent protection, thermal cutoffs, and insulation that make idle-state fires virtually impossible. A counterfeit charger lacking these protections represents a qualitatively different risk category. UL independently tested 400 counterfeit Apple 5W chargers and found a 99% failure rate (Release 20PN-27). The charger fire risk is almost entirely a product-quality problem, not an inherent physics problem.
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[3] University of Melbourne (Dr. Glen Farivar, Dept. of Electrical and Electronic Engineering) — Is it OK to leave device chargers plugged in all the time?
Is it OK to leave device chargers plugged in all the time?- Statistic
Modern chargers in no-load mode consume less than 1 W; fire risk from a certified idle charger is negligible- Excerpt
“"Modern chargers have smart power management that keeps them in sleep mode until a device draws power. A no-load charger typically consumes less than 1 watt. The fire risk from a certified charger left plugged in with no device is minimal." ”
- Source data from
- 2025-03-01
- Accessed
- 2026-04-24 · archived copy
- Calculation
- Dr. Farivar's expert analysis provides the physics basis for the negligible risk assessment. At 0.1 W (typical phone charger no-load), the heat dissipation is roughly equivalent to a single grain of rice being warmed per second -- physically incapable of igniting any surrounding material under normal conditions. Even a laptop charger at 4.4 W no-load generates less heat than a night-light.