Underground Transformer Explosion in León, Guanajuato.

Grupo Edmar
Sep 12
3 min read

September 12, 2025 - Underground Transformer Explosion in León

What happened in León? Recent events.

In the first week of September 2025, León, Guanajuato, experienced moments of tension when two underground transformers exploded in the city center . The first of these incidents occurred on Saturday, September 6, injuring eleven people, including bystanders and local merchants. Some of the injured suffered severe burns and were taken to nearby hospitals.

The second incident occurred just two days later, on Monday, September 8, at the intersection of Benito Juárez and Reforma streets. Fortunately, no one was injured in this incident, but power outages, street closures, and immediate mobilization of authorities were reported.

Neighbors and witnesses reported that signs of failure had already been observed before these explosions, such as strange noises, sparks, and small pops, indicating that the transformer had pre-existing problems that were not addressed in a timely manner.

Probable causes and actions of the authorities

Initial reports indicate that overheating in the cooling system may have been one of the main causes. This type of failure is common when the transformer is operating beyond its capacity or when it is not properly maintained .

Following the incident, the Federal Electricity Commission (CFE) coordinated efforts with Civil Protection, the Fire Department, and the Ministry of Security to secure the area, conduct technical inspections, and ensure there was no risk of another explosion. It was also reported that other underground transformers in the area would be inspected to rule out similar damage or failures.

This type of rapid response is important, but the key is to act before problems escalate. A preemptive review would have significantly reduced the likelihood of these explosions occurring.

Risks of not properly maintaining electrical transformers.

A transformer is a key component of the electrical grid. When it isn't properly maintained, the risks increase over time:

Internal overheating: caused by overloads or failures in the cooling system.
Insulation deterioration: Moisture, dust, or lack of cleanliness reduces the transformer's ability to operate safely.
Dielectric oil corrosion and leaks: These directly affect performance and can cause fires.
Electrical faults due to vibrations or poor connections: a loose screw can trigger an electric arc.

In León's case, witnesses mentioned early signs of trouble, such as sparks and strange odors. If these had been addressed promptly, the risks would have been lower.

Importance of purchasing equipment with quality certifications and brands.

Companies or authorities often opt for cheaper transformers, without considering that cheap can be expensive. The difference between a certified transformer and one that hasn't been tested can mean the safety of hundreds of people.

Teams with national and international certifications undergo tests of:

Electrical and thermal resistance.
Energy efficiency.
Safety in case of overloads.
Durability of insulating materials.

In addition, reputable manufacturers offer warranties, technical support, and availability of spare parts, ensuring operational continuity.

Preventive and Corrective Maintenance.

Transformer maintenance can be divided into two types:

Preventive maintenance : periodic inspections, insulation resistance testing, cooling system inspection, component cleaning, and temperature recording. This type of action prolongs the transformer's lifespan and prevents emergencies.
Corrective maintenance : Applied when a fault already exists, such as oil leaks, burned components, or damaged connections. Although necessary, this type of maintenance is always more expensive and risky.

A well-planned preventive maintenance program can reduce the likelihood of serious failures by up to 70% . León's case reminds us that waiting for a problem to become apparent can have very costly consequences.

Costs of Ignoring Quality or Poor Maintenance.

The costs of an explosion like the one in León are not limited to material damage to the equipment:

Economic: repair, replacement of transformers, expenses on damaged infrastructure.
Social: injured people, affected families, and distrust in public infrastructure.
Commercial: Downtown businesses that lost sales during the blackouts and closures.
Legal: possible lawsuits or civil liabilities in case of injuries.

Investing in a certified transformer and an appropriate maintenance plan is much more cost-effective than dealing with the consequences of an explosion.

The role of specialized providers in prevention.

One of the most important lessons learned from what happened in León is that simply installing a transformer isn't enough; a combination of reliable equipment, regular maintenance, and specialized technical support is required. Having manufacturers and suppliers that work under official standards and certifications makes a significant difference to the safety of facilities.

In Mexico, there are companies with proven experience in the manufacture and maintenance of high-quality transformers, such as Grupo Edmar , which in addition to providing certified equipment also offers technical support to ensure safe operation over time.