Just after 3.48 a.m. on May 3, 2026, fire ripped through a four-storey building in Vivek Vihar, East Delhi, killing nine. The suspected origin was an AC blast or short circuit.
Ten newborns died in an overcrowded Jhansi NICU in November 2024, a unit meant for 18 babies packed with 55. Three newborns in Amravati this August, dead not from flame but from smoke inhalation, even though the fire itself was out within 30 minutes. One newborn in Chhindwara two days before that. Ten patients at Cuttack’s SCB Medical College this March, when a short circuit in a trauma-ICU air-conditioner ignited an oxygen-rich ward at 3 a.m.
Fire accidents in India used to happen in industrial units, firecracker factories and mass gatherings. No more. The more devastating ones happen right in our neighbourhoods, in hospitals and high-rises. They are almost always triggered by electrical fires.
Delhi Fire Service attributes over 80% of the capital’s fires to electrical faults. Mumbai Fire Brigade, analysing 26,855 incidents over five years, attributes nearly three in four to the same cause. New Delhi alone saw a 37% rise in residential fires this year over last, with roughly 70% traced to short-circuiting, faulty wiring, overheating, and overloaded circuits. The National Crime Records Bureau recorded 7,566 fire accidents and 7,435 deaths in 2022, with short circuit consistently among the largest single causes.
Indian electricity demand hit 256.11 GW on April 25 this year, against air temperatures of 47 degrees, roughly double the early-2010s peak. A/Cs draw about 50 GW at peak. And projections place the A/C load at 180 GW in another 10 years. Indians bought more than 15 million air-conditioners in 2025 alone, and the International Energy Agency expects the installed base to climb from 93 million units in 2024 to 240 million by 2030.
Air-conditioners draw heavy current that electrical systems in older buildings are unable to withstand, resulting in the wiring burning up. What’s called an A/C blast is the overworked compressor in the refrigeration exploding due to sheer heat caused by overworking. Investigation into these fires has been hampered by shortage of certified fire forensic investigators. Too often, the causes are dismissed as blasts or short circuits. Root cause analysis and systemic remedies are rarely formulated.
How electrical fires happen?
An electrical circuit has three parts. The load is whatever draws current. It could be just a light or an air-conditioner. The wiring carries that current, insulated to keep two conductors from touching. The protection device, typically a miniature circuit breaker, is meant to cut the current flow the instant something goes wrong. The circuit breaker switches off the current within about a tenth of a second for a short circuit, or within a longer window, from a minute to an hour, for a sustained overload. A fire needs two failures at once: something in the load or wiring goes wrong, and the protection device fails to trip in time.
A peer-reviewed 2025 review in the journal Fire identifies six recurring failure modes behind that first failure: short circuits, overloads, loose or oxidised connections, series and parallel arc faults, ground faults, and equipment ageing. Of these, a loose connection is often the quietest killer. Research on wiring practice, cited in Indian engineering literature reviewing fire risk in electrical installations, shows that loose terminal connections, whether from bad workmanship, thermal expansion and contraction, or simple ageing, create a phenomenon called glowing contact: a slow-building hot spot that can smoulder in a wall or panel for months before anything is visible from outside.
There is a second, slower mechanism that gets far less attention and could explain a great deal about how India’s fires happen: harmonics. Every inverter-driven air-conditioner, along with every UPS, LED driver, ventilator and EV charger, draws current in short, jagged pulses rather than a smooth wave. This injects distortion into the electrical supply at multiples of the base 50 Hz frequency. In three-phase buildings, certain harmonic orders, called triplen harmonics, do not cancel out in the neutral conductor the way normal, balanced current does. Instead they add up. The neutral wire, which was never designed to be load-bearing and carries no circuit breaker of its own, quietly overheats. A loose joint nearby could make an overheated neutral become an ignition source ripping up ordinary insulation.
Fire investigators suspect that many chemicals and solvents are used in ICUs and the vapours they generate don’t get evacuated well-known enough because of poor maintenance of ventilation systems. They point out that ICUs have dedicated ventilation systems and need much care. While these vapours provide the fuel, a source of heat is required for ignition. And that is where harmonics-generated heating could come into play, says a fire forensic engineer who didn’t wish to be named. “Electrical fires are a gray area and require a lot of precautions. Sadly, in India, compliance with regulations is considered a financial burden,” he adds.
Medical equipment damaged after a fire broke out in the neonatal intensive care unit of a government hospital killing three newborns, in Amravati district of Maharashtra.
| Photo Credit:
EMMANUAL YOGINI
Among the first cases of a spectacular failure due to harmonics happened in September 2010, when a capacitor inside a harmonic filter aboard the cruise liner Queen Mary 2 failed while the ship approached Barcelona with 3,823 people aboard. The explosion blacked out the vessel.
Investigators from the UK’s Marine Accident Investigation Branch found that the ship’s only warning system, a current-imbalance detector meant to flag a degrading capacitor, had been silently broken for years, and nobody knew. The capacitor had likely been failing since 2006. Regular inspections had “passed” the unit on paper using tests that were, on the ship’s own sealed equipment, physically impossible to perform properly. The UK’s Maritime and Coastguard Agency issued a formal notice afterward warning the shipping industry that harmonic distortion, if left unchecked, can shorten equipment life and “potentially result in fire”.
The shipping industry has since then been probing harmonics angle in several accidents including the Dali case where an Indian-managed and crewed container ship rammed a bridge in Baltimore, U.S., leading to the highest-ever marine accident insurance payout in history.
Where does India fall short?
A 2023 peer-reviewed analysis in the Journal of Failure Analysis and Prevention, examining Indian hospital fires since 2010, found that electrical short circuits accounted for 89% of all hospital fire outbreaks, with at least half the hospitals studied in documented non-compliance with fire-safety norms.
The Ministry of Health and Family Welfare revised its National Guidelines on Fire and Life Safety in Healthcare Facilities in 2026 which say plainly that electrical faults, specifically short circuits and malfunctioning air-conditioners or medical equipment, are the predominant cause of hospital fires in India. It adopts the international Group 0/1/2 classification of medical locations by electrical risk, requires Medical IT systems with insulation monitoring and fault-location devices in ICUs and operating theatres, and lays out a genuinely detailed testing regime, insulation resistance, earth-leakage tripping, protective-device coordination, at defined intervals of 12 and 36 months. It even specifies fire-extinguisher classes by hazard type, which would have caught the wrong-extinguisher problem reported at Jhansi.
The report prescribes fire safety certificates, audits and mock drills with real specificity in the new guidelines, but they remain, as before, dependent on State rules and largely self-reported compliance, with no penalty structure of the kind that would make a hospital treat an electrical audit as more than paperwork.
Moreover, hospitals, especially ICUs, are loaded with state-of-the-art electronic devices. Ventilators, infant warmers and phototherapy units (relevant to the Chhindwara accident), oxygen concentrators (relevant to Jhansi/Vivek Vihar), anaesthesia machines and ventilator-integrated ICU beds, CT scanners, MRI machines, inverter A/Cs and dialysis machines are heavy harmonics generators.
But the report does not mention harmonics, total harmonic distortion, or power quality. India’s most current hospital fire-safety document treats “electrical safety” as a matter of insulation, earthing and load capacity alone.
The Bureau of Indian Standards’ newly revised National Building Construction Standards 2026, the country’s overarching building code, is the first version to define harmonics explicitly, require load calculations that account for them, and mandate that buildings with heavy non-linear load plan for active filtering at the design stage. It closes a specific, long-standing loophole: Indian practice had allowed a half-size neutral conductor in three-and-half-core cabling, adequate for the balanced loads of an older era but not for a neutral now carrying triplen harmonics on top of ordinary current. The 2026 code mandates full four-core cable for internal wiring instead, precisely to stop the neutral from quietly overheating. It also lists, for the first time, an Indian standard for arc-fault detection devices, IS 17121, adopting the same IEC standard behind America’s AFCI mandate.
The arc-fault detection is listed among the code’s accepted reference standards but is not actually mandated anywhere in the operative text, unlike residual current devices, which the code requires repeatedly. A standard existing on paper is not the same as a clause requiring its use. Further, the code’s rigorous regime, power-quality monitoring, arc-flash hazard analysis, thermography-based inspection, tiered maintenance schedules, are all written specifically for data centres, not for hospitals, homes or the ordinary commercial buildings where, as this year’s numbers from Delhi and Mumbai show, most of India’s electrical fires actually occur. The text specifies that periodic inspection and testing for installations below the “notified voltage,” which covers the overwhelming majority of Indian homes, hospitals and small commercial buildings, is self-certified by the owner rather than independently verified by an Electrical Inspector. More fundamentally, the NBCS, like the national codes before it, is written for buildings still to come. Its requirements apply as new buildings are constructed or as existing ones are formally altered; the code’s own text exempts existing buildings from its new requirements entirely unless they are altered, or a local authority separately judges them hazardous.
There is no mechanism that reaches back into the country’s existing building stock and brings it up to the 2026 standard on any fixed timeline. That means the older wiring installed under weaker rules, in Amravati, Jhansi and Vivek Vihar, or even in the Kolkata fires, will keep operating exactly as it is. In any case, renovation and repurposing often happens on the sly, is unregulated and therefore under the safety audit radar.
Field data from Delhi and West Bengal, gathered by The Energy and Resources Institute for two of the country’s largest electricity distribution utilities, shows harmonics is not an abstract worry. As rooftop solar and other non-linear loads rise on real low-tension feeders, on-site harmonic measurements already show distortion levels climbing toward, and in places past, the very IEEE 519 thresholds India has chosen not to enforce inside buildings.
India lacks the fire-forensic engineering capacity to distinguish, after the fact, between a generic short circuit and a harmonic-driven neutral failure. Most post-fire accounts stop at “electrical fault” or “technical fault”, language broad enough to close the file without ever identifying the actual failure mode, and in doing so, without ever generating the kind of evidence that would justify updating a standard.
West Bengal: the retrofit problem
West Bengal serves as an egregious case of what is everywhere in India. Densely populated urban neighbourhoods featuring buildings built for another era of low electrical loads being repurposed for a much more electrically heavy application. Since 2025, the State has recorded six major building fires, three of them in hotels and two in godowns, killing roughly 65 people, a disproportionate number of them migrant workers and pilgrims.
The pattern in each case traces directly back to the mechanism at the centre of this piece: old buildings, never engineered for the load now running through them, repurposed without anyone reassessing what the wiring could actually carry. The Shikha Inn, gutted by fire on Mirza Ghalib Street in central Kolkata, occupied a century-old building that was not built to be a hotel at all; five separate hotels operated across its five floors. As with much of India’s old commercial building stock, its electrical systems were sized for a different era, then loaded, piecemeal and without engineering review, with air-conditioners and other equipment. The August 17 fire at a hotel in Tarapith followed a similar trajectory: an electrical origin, and a death toll driven less by flame than by smoke, worsened by the use of flammable material in the hotel’s interior. Rituraj Hotel, which burned in April 2025, had also been repurposed from its original use, and had only one stairway; when fire broke out on the first floor, it cut off the sole escape route, trapping guests on the upper floors in smoke exactly as at Mirza Ghalib Street.
What makes West Bengal’s cluster an especially sharp illustration of the national problem, rather than a separate one, is how closely it mirrors the failure already documented in hospitals. Undocumented load growth on old wiring, safety measures that exist on paper without being verified in practice, and an accountability structure that responds to disaster with promises, in this case a statewide fire safety audit, rather than with sustained correction of the underlying infrastructure.
What needs to be done
It is worth being precise about what “addressing harmonics” would actually require, since good equipment already exists. Many quality inverter ACs and medical devices include some internal filtering or power-factor correction, tuned to that single device. But this filtering is a manufacturer’s design choice calibrated to the appliance alone, not to the building it sits in, and cheaper appliances often skip it entirely. Even where every individual device filters its own output well, none of that filtering is designed to work in concert with the others.
A ward or a home may have a dozen separately filtered, well-behaved appliances whose combined harmonic signature still overwhelms a shared neutral conductor sized for an earlier, simpler load, because nothing at the building level coordinates or caps what they collectively put onto that wire. The new code’s data-centre-grade rules, mandatory total-harmonic-distortion limits referencing IEEE 519, periodic THD measurement at distribution boards, panel-level filters above a defined load threshold, and neutral-conductor thermal monitoring may well need to be expended to hospitals and heavy-load commercial buildings.
There have been cases of root cause analysis by Indian agencies. But these are sporadic. A published, root-cause forensic chain after every major electrical fire will name the precise mechanism of failure rather than settling for “short circuit”.
Fire-NOC renewal should be tied to licence, not just self-certification. Sprinklers, even if they activate, are inadequate for heavy duty fires especially electrical. CO2 or clean-agent extinguishers specifically for ICUs and electrical panel rooms, not the ABC-type units reportedly used at Jhansi, would add to firefighting capabilities of hospitals. The new Health Ministry guidelines now specify this. For repurposed buildings of the kind seen in Kolkata’s hotel fires, a mandatory second stairway and an engineering reassessment of electrical load should be non-negotiable conditions of the change-of-use approval itself, not left to a subsequent, and largely theoretical, audit. For individual building owners, a power-quality audit and periodic thermography scan of the main panel, not just a load check, alongside ISI-marked wiring and modern combined circuit-breaker and earth-leakage devices replacing decade-old MCBs needs to be mandatory.
