{
  "slug": "charger-left-plugged-in-fire",
  "question": "What are the odds of a house fire from leaving a charger plugged into the wall?",
  "category": "tech",
  "tags": [
    "household"
  ],
  "no_reliable_estimate": false,
  "perceived": {
    "description": "\"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.\n",
    "rough_estimate": "~1-5% lifetime chance of a fire from a plugged-in charger",
    "kind": "intuition"
  },
  "native": {
    "display": "~0 documented fires from certified chargers left plugged in with no device attached",
    "numerator": 1,
    "denominator": 10000000,
    "unit": "estimated annual fire probability per certified idle charger (no documented incidents)",
    "population": "certified (UL/CE) phone and laptop chargers plugged into wall sockets without a device, US/UK"
  },
  "normalized": {
    "lifetime_us_adult": 0.000005,
    "display": "~0.0005% lifetime probability of a fire from a certified idle charger over 40 years (effectively zero)",
    "log_value": -5.3,
    "assumptions": "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.\n",
    "uncertainty": {
      "low": 1e-7,
      "high": 0.0001
    },
    "scope": "us_adult_lifetime"
  },
  "sources": [
    {
      "url": "https://www.nfpa.org/education-and-research/research/nfpa-research/fire-statistical-reports/home-fires-caused-by-electrical-distribution-and-lighting-equipment",
      "title": "Home Fires Caused by Electrical Distribution and Lighting Equipment",
      "publisher": "National Fire Protection Association (NFPA)",
      "source_type": "reputable_reference",
      "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.\"\n",
      "source_date": "2023-01-01",
      "source_accessed": "2026-04-24",
      "archive_url": "http://web.archive.org/web/20251210090543/https://www.nfpa.org/education-and-research/research/nfpa-research/fire-statistical-reports/home-fires-caused-by-electrical-distribution-and-lighting-equipment",
      "calculation_notes": "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.\n"
    },
    {
      "url": "https://www.electricalsafetyfirst.org.uk/media-centre/press-releases/2017/12/ninety-eight-per-cent-of-fake-or-lookalike-iphone-chargers-put-consumers-at-risk-of-lethal-electric-shock-and-fire/",
      "title": "98% of fake iPhone chargers fail safety tests",
      "publisher": "Electrical Safety First (UK charity)",
      "source_type": "reputable_reference",
      "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.\"\n",
      "source_date": "2017-12-01",
      "source_accessed": "2026-04-24",
      "archive_url": "http://web.archive.org/web/20260525092858/https://www.electricalsafetyfirst.org.uk/media-centre/press-releases/2017/12/ninety-eight-per-cent-of-fake-or-lookalike-iphone-chargers-put-consumers-at-risk-of-lethal-electric-shock-and-fire/",
      "calculation_notes": "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.\n"
    },
    {
      "url": "https://eng.unimelb.edu.au/ingenium/is-it-ok-to-leave-device-chargers-plugged-in-all-the-time",
      "title": "Is it OK to leave device chargers plugged in all the time?",
      "publisher": "University of Melbourne (Dr. Glen Farivar, Dept. of Electrical and Electronic Engineering)",
      "source_type": "reputable_reference",
      "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.\"\n",
      "source_date": "2025-03-01",
      "source_accessed": "2026-04-24",
      "archive_url": "http://web.archive.org/web/20260226003753/https://eng.unimelb.edu.au/ingenium/is-it-ok-to-leave-device-chargers-plugged-in-all-the-time",
      "calculation_notes": "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.\n"
    }
  ],
  "comparison_anchors": [
    {
      "label": "Home fire death (lifetime, US)",
      "lifetime_us_adult": 0.0025
    },
    {
      "label": "Lightning strike death (lifetime, US)",
      "lifetime_us_adult": 0.000013
    },
    {
      "label": "Asteroid impact death (lifetime, global)",
      "lifetime_us_adult": 7.4e-7
    }
  ],
  "personal_factor_multipliers": [
    {
      "factor": "using a counterfeit or uncertified charger",
      "multiplier": 10000,
      "notes": "98-99% of tested counterfeits fail safety checks; lacking thermal cutoffs and overcurrent protection, they represent a qualitatively different risk category even in idle mode"
    },
    {
      "factor": "actively charging a lithium-ion device (e-bike, power bank)",
      "multiplier": 100000,
      "notes": "Virtually all documented charger fires involve active charging of lithium-ion batteries; London Fire Brigade attended 206 e-bike/e-scooter fires in 2025 alone"
    },
    {
      "factor": "charger with visible damage (frayed cable, cracked housing)",
      "multiplier": 1000,
      "notes": "Physical damage can expose conductors or compromise insulation, creating arc-fault potential even at low power draw"
    },
    {
      "factor": "charger covered by fabric or placed on a soft surface",
      "multiplier": 50,
      "notes": "Covering a charger traps even minimal heat; fire services specifically warn against charging devices on beds or under pillows, though this primarily applies to device-attached charging"
    }
  ],
  "short_label": "Charger left plugged in",
  "myth_framing": "overrated",
  "outcome_severity": "fatal",
  "exposure_pattern": "cumulative",
  "outcome_type": "death",
  "valence": "negative",
  "caveats": "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.\n",
  "quality_score": {
    "d1": 3,
    "d2": 5,
    "d3": 4,
    "d4": 4,
    "d5": 4,
    "d6": 5,
    "d7": 5,
    "d8": 5,
    "avg": 4.375,
    "scored_by": "extracted-from-transcript",
    "scored_at": "2026-04-26",
    "methodology_version": "1.0"
  },
  "reviewer": "8d-quality-review-agent",
  "last_reviewed": "2026-04-26",
  "reviewed": true,
  "generated_at": "2026-04-24",
  "image": {
    "alt": "A phone charger plugged into a wall socket with no device attached, flat vector illustration in muted tones."
  },
  "attribution": "Likelier — https://likelier.app",
  "license": "https://creativecommons.org/licenses/by-sa/4.0/",
  "support": "https://buymeacoffee.com/kgluszczyk?via=likelier&utm_content=api-fear-single",
  "canonical_url": "https://likelier.app/charger-left-plugged-in-fire"
}