I have spent the better part of one decade working in and around hydropower projects in Nepal — from the steep gorges of the Trishuli basin to the high-altitude run-of-river schemes pushing into the upper Himalayan ranges. I have walked through powerhouses during monsoon floods and during the bone-dry winds of late spring. I have reviewed O&M manuals that referenced Indian Standards because no Nepali standard adequately covered the situation. And I have sat in post-incident meetings where the root cause of an equipment failure was ultimately traced not to geology, not to the river, but to something that started with a spark and a little oil.

Fire, in the context of Nepal's hydropower sector, is a subject that rarely appears at the top of any risk register. Dam break analysis, glacial lake outburst floods, landslide-induced surges, seismic vulnerability — these are the hazards that dominate our technical discourse, and rightly so. Nepal's hydropower history is full of flood-related tragedies. But the fire risk that sits quietly inside every powerhouse, every underground transformer cavern, every cable gallery cut into living rock — this risk tends to get a polite acknowledgement in a project's safety documentation and then very little else.

I write this article because I believe that needs to change, and I write it now because Nepal's hydropower ambitions have never been larger, or more consequential.

Nepal's Hydropower Moment — and What It Demands

Nepal has set a target of harnessing approximately 15,000 MW of hydropower by 2030. In fiscal year 2023/24, the country exported nearly two billion units of electricity to India — a figure that would have seemed extraordinary just a decade ago. Export to Bangladesh has begun. The sector draws international financing, bilateral partnerships, and the aspirations of a generation of Nepali engineers who see hydropower as the engine of the country's economic future.

With this expansion comes infrastructure of increasing complexity and scale. Underground powerhouses. Long headrace tunnels. Transformer caverns carved into metamorphic rock. High-voltage switchyards perched on narrow terraces above raging rivers. These are not small, simple machines. They are sophisticated industrial facilities operating in some of the most geologically dynamic and remotely accessible terrain on earth. And they carry, within them, the full catalogue of fire hazards that any large hydroelectric facility carries anywhere in the world.

Oil-filled step-up transformers holding thousands of liters of mineral oil. Combustible hydraulic oil running turbine governing systems. Dense cable trays threading through every floor. Generator windings insulated with materials that can sustain combustion. Hot-work activities — welding, cutting, grinding — conducted routinely during maintenance overhauls in enclosed underground spaces.

These hazards are not unique to Nepal. But the consequences of a fire in a Nepali Himalayan powerhouse are shaped by factors that make them potentially more severe than anywhere else: extreme remoteness, road access that monsoon flooding can cut for weeks, limited mutual-aid fire response capacity in mountain districts, underground facilities with constrained egress, and project economics where months of forced outage can threaten the financial viability of an entire scheme.

What I Have Seen in the Field

Let me be direct about what I observe when I conduct site reviews at hydropower facilities across Nepal.

Fire detection systems are often installed as a compliance requirement — to satisfy lenders' technical specifications or project agreements — rather than as a genuinely integrated part of how the facility is operated and maintained. Detectors are present. Annunciator panels exist. But I have encountered plants where detector heads in transformer bays had not been tested in years. I have seen CO₂ suppression cylinders for enclosed switchgear rooms with pressure gauges that had drifted below the minimum mark. I have reviewed fire response plans that listed a "dedicated fire response team" whose members had rotated out of the project entirely.

None of this is the result of malice or indifference. It reflects a sector-wide prioritization problem. Operations teams at remote hydropower facilities are small, often stretched thin, focused intensely on generation targets and mechanical availability. Fire protection maintenance — periodic detector testing, suppression system checks, fire drill execution, cable penetration seal inspections — tends to slip when it competes with the urgent operational demands of keeping the machines turning.

I have also observed the challenge that Nepal's regulatory environment creates. The Department of Electricity Development's O&M guideline for hydropower plants does reference fire protection requirements, drawing where necessary on Indian Standards. But there is no dedicated, enforceable Nepali standard specifically governing fire protection systems at hydropower facilities — no equivalent of NFPA 851 calibrated to our context. The result is that fire protection specifications at individual projects are largely driven by the requirements of international lenders or equipment suppliers, and once those agreements are signed and the project commissioned, ongoing verification of fire protection standards tends to weaken.

The Underground Problem

I want to dwell specifically on underground powerhouses, because this is where Nepal's topography intersects most dangerously with fire risk.

A significant proportion of Nepal's larger hydropower projects house their generating equipment underground — in caverns excavated from rock, accessed through tunnels, with the surface potentially hundreds of meters above. This architecture is often necessary: the gradient of Himalayan rivers is so steep that surface powerhouses would sit in flood paths, be buried in landslide debris, or simply be impractical to protect. Underground is safer from the river. It is not safer from fire.

What differentiates underground hydro powerhouses from almost any other industrial fire environment is the combination of limited access, restricted egress, constrained ventilation, and the presence of large quantities of flammable liquids and cables in a confined space. A fire that might be manageable in a surface facility — contained in one room, accessible to fire response from multiple directions, with natural ventilation carrying smoke away — becomes categorically more dangerous underground.

The Srisailam disaster in India in August 2020 — nine lives lost — unfolded in exactly this context. The underground plant had a single entry and exit point. A fire in the control room on the upper floor blocked the only means of escape. Workers were found at the base of the two-kilometer exit tunnel.

Nepal has no plant identical to Srisailam. But the structural logic — underground, limited egress, fire in the upper control level — applies to multiple facilities operating across our country today. I raise this not to alarm, but because engineering colleagues who have never experienced an underground powerhouse fire sometimes underestimate how quickly smoke propagation through interconnected tunnels and ventilation ducts can render egress routes unusable.

The life safety code provisions governing exit travel distances, exit discharge points, emergency lighting circuits, and pressurized stairwells exist because engineers learned from incidents. Nepal needs to apply those lessons proactively, before an incident here teaches them again.

The Transformer: Our Most Significant Fire Hazard

If I were asked to identify the single greatest fire hazard at a typical Nepali hydropower plant, I would say, without hesitation, the main step-up transformer.

Large power transformers contain significant volumes of mineral insulating oil — an excellent dielectric, but a flammable liquid with real ignition potential when it contacts a hot surface or electrical arc. A transformer fault that ruptures the tank under pressure can produce a spray of burning oil across a wide area. In an underground transformer cavern, this is a contained catastrophe: limited ventilation, rock walls that reflect heat and block suppression access, and a fire load that can sustain combustion long after the original fault has cleared.

History provides the pattern. In 1992, a lightning-induced voltage surge caused a transformer explosion in the underground transformer cavern of a pumped-storage plant in Taiwan. In Nepal, where our transmission corridors are exposed to significant lightning activity and our grid experiences voltage transients that older transformer insulation systems may be ill-equipped to handle, the risk is not hypothetical.

Standard fire protection for outdoor transformers — a deluge system that floods the transformer bund with water on fire detection — is relatively well understood and implemented in Nepal's newer projects. The challenge is older facilities, where transformer bund drainage may not be properly designed to prevent burning oil from migrating along cable trenches or conduits into adjacent areas. Oil containment bunds that are undersized, improperly sloped, or degraded by years of exposure and neglect remove the passive protection that prevents a transformer fire from becoming a facility fire.

I have recommended transformer bund remediation at more than one facility where this deficiency existed. The cost is modest. The risk reduction is significant.

The Cable Gallery: A Fire Pathway Hidden in Plain Sight

Second to the transformer, cable galleries are where my attention goes in any site review.

Loss data from the hydropower sector internationally is consistent: fires involving electrical cables and equipment — not generators, not transformers — account for the highest proportion of fire incidents at hydroelectric facilities. Cables burn. Cable trays serve as pathways along which fire can travel from the origin point into adjacent rooms, adjacent levels, and adjacent systems. Concrete structures can be damaged through spalling when cable fires burn hot enough and long enough. If cables cannot be spliced, replacement requires stripping entire runs — a project of months, not weeks.

In Nepal, the firestopping discipline around cables is an area of persistent concern. Cables running through fire-rated walls and floors must be sealed with listed, fire-rated penetration seals — materials that expand when heated and prevent fire and smoke from migrating through the opening. I regularly encounter penetrations that were sealed during construction with ordinary mortar, expanding foam, or nothing at all. The fire-rated wall then provides no actual fire separation because every cable penetration is a bypass.

This is not a criticism unique to Nepal. It is a global problem in the construction of complex industrial facilities. But it is a problem that the hydropower sector in Nepal has not yet confronted systematically, and it is one that a future fire will eventually force us to address.

A Call to Action: Five Things Nepal Must Do Now

I write as a consultant, not as a regulator or as a critic. My aim is constructive. Based on my years in this sector, I believe there are five actions that Nepal's hydropower community — engineers, operators, developers, regulators — must take to meaningfully improve fire protection across our installed and under-construction fleet.

First, develop a Nepal-specific fire protection standard for hydropower facilities. The reliance on referenced Indian Standards, adapted informally to our context, is no longer adequate as our installed capacity scales and our facilities grow more complex. The Department of Electricity Development, in collaboration with Nepal Engineers' Association and the hydropower industry, should develop a dedicated fire protection guideline that addresses our specific geology, our underground powerhouse prevalence, our remote-site emergency response context, and our workforce realities. It does not need to be invented from scratch — NFPA 851 and the international body of practice provide an excellent foundation — but it must be ours, enforceable, and regularly updated.

Second, mandate periodic third-party fire protection audits as a condition of operating license renewal. Self-assessment by site operations teams — always under resource pressure, always focused on availability and generation — is insufficient. Independent fire protection reviews, conducted by qualified professionals, at regular intervals, should be a regulatory requirement. Deficiencies found must be documented, scheduled for remediation, and verified as corrected. This is how dam safety works in Nepal today. There is no principled reason fire protection should be treated differently.

Third, treat fire protection maintenance as mission-critical, not optional. Suppression system inspection schedules, detector testing frequencies, cable penetration seal integrity checks, and fire drill programs must be built into O&M plans with the same rigor as turbine maintenance and electrical testing schedules. Plant managers need to be empowered — and held accountable — for delivery of fire protection maintenance, not just generation targets.

Fourth, conduct honest egress assessments at all underground facilities. For every underground or semi-underground powerhouse in Nepal's fleet, operators should conduct a walk-through egress audit: How many independent exit routes exist? What is the maximum travel distance to a safe area? What happens to those routes if a fire occurs on the control floor, the cable gallery floor, the transformer level? What emergency lighting is available on independent power circuits? Is there a smoke management system — or at minimum, a ventilation design that does not channel smoke across egress routes? These questions have answers. In too many facilities, the answers have never been formally sought.

Fifth, invest in workforce fire safety training that is scenario-based and site-specific. Generic fire safety induction training — the kind that covers evacuation in the abstract and demonstrates a portable extinguisher — is not sufficient preparation for the reality of a fire in an underground powerhouse. Scenario-based training, conducted in the actual facility, with timed evacuations and post-exercise critique, builds the muscle memory and institutional knowledge that determines whether workers survive a real event. Research on hydropower construction safety in Nepal and South Asia has consistently found that scenario-based, site-specific training is substantially more effective than general safety orientation. The same applies to fire response.

The Wider Context: Wildfire and the Himalayan Perimeter

Before I close, I want to name a risk that sits outside the powerhouse but is becoming impossible to ignore.

Nepal's fire incident data shows a sharp rise in fire occurrences from 2023 to 2024, linked to dry conditions and climate change — a pattern consistent with what we are seeing across the Himalayan region. Nepal's mean annual temperature is rising at approximately 0.06°C annually, and the Himalayan region is warming faster than the rest of the country. Drier springs, stronger winds, and longer periods between significant rainfall are creating conditions in which wildfires burn larger, spread faster, and reach terrain where they previously did not.

Many of Nepal's hydropower facilities sit in precisely the kinds of steep, forested gorges and ridgelines that are most vulnerable to wildfire spread. Transmission corridors traversing forested hillsides, switchyards with limited perimeter clearance, access roads whose closures would prevent emergency response — these are real vulnerabilities that the hydropower sector has not yet formally integrated into its hazard management frameworks.

The lessons from global experience are clear: a comprehensive fire protection strategy for a remote mountain hydropower facility must account for the fire that arrives from outside, not only the fire that starts within. Vegetation management around electrical infrastructure, firebreak maintenance along transmission corridors, and pre-positioned firefighting equipment with trained personnel are components of that strategy.

Conclusion: The River Cannot Burn, But the Powerhouse Can

I return to the site supervisor's words with which I began. He was not wrong about the river. But the powerhouse is not the river. The powerhouse is an industrial facility, built by human hands, filled with human decisions about what risks to protect against and what risks to leave for another day.

In Nepal, we have built remarkable things — underground generating halls that would impress any engineer in the world, run-of-river schemes that harness some of the highest-gradient rivers on earth, transmission infrastructure stitched across terrain that defies easy description. Our engineers are capable and committed. Our sector is growing in sophistication.

The next step in that growth is to take fire protection as seriously as we take the river. To build fire protection systems that work on the day they are needed, maintained by teams that know how to operate them, in facilities designed so that workers can find their way out in the dark.

The river cannot burn. But we can do better for the people who work beside it.

Er. Manish Nidhi is an independent consultant specializing in Firefighting engineering and safety, with over one decade of experience across projects in Nepal. The views expressed in this article are his own.

Key references: NFPA 851 – Recommended Practice for Fire Protection for Hydroelectric Generating Plants; NFPA 850 – Fire Protection for Electric Generating Plants; Department of Electricity Development (GoN) – Guidelines for O&M of Hydropower Plants; International Journal of Fire and Materials Science; POWER Magazine hydropower loss records; Nepal NDRRMA disaster incident data 2024–25.