Rats and trees contributed to 2025 islandwide blackout, report says
Puerto Rico's energy regulator found that rodent damage to a protection cable, inadequate vegetation management and a failed breaker worsened an initial fault on April 16, 2025.
PhotoThe short version
- Metro Puerto Rico reported that the NEPR final report dated Sept. 21 2026 found deficiencies in protection systems at Cambalache and Costa Sur plus communication channels
- Metro Puerto Rico reported the blackout cascaded and caused total system collapse in less than 20 seconds after the tree contact on line 50100
- El Nuevo Día, Primera Hora and Metro Puerto Rico reported an aerial patrol of the line five days earlier failed to detect the problematic vegetation
- The Negociado de Energía ordered LUMA to strengthen internal inspections, expand maintenance protocols and reinforce vegetation management
Updates
Update, Oct 15, 3:30 PM AST
Metro Puerto Rico adds that the blackout cascaded in under 20 seconds, notes deficiencies at Costa Sur and in communications, and states the NEPR requires LUMA to submit a public version of its own analysis.
Metro Puerto Rico reported that the fault spread after deficiencies were found in protection systems at both the Cambalache and Costa Sur substations as well as in communication channels. This caused the disconnection of generating units and the total collapse of the electrical system in less than 20 seconds. Metro Puerto Rico reported.
The new report states that although the Negociado de Energía recognized that LUMA had implemented corrective measures, it still found the company's inspections and preventive maintenance practices insufficient to identify critical conditions including corrosion, deterioration and rodent presence. The regulator ordered LUMA to strengthen internal inspections, expand maintenance protocols and reinforce vegetation management on transmission lines. Metro Puerto Rico reported.
According to Metro Puerto Rico, the final report dated Sept. 21, 2026 also requires LUMA to present a public version of its own analysis prior to the closing and archiving of the case.
Update, Oct 15, 3:02 PM AST
Primera Hora reports LUMA's statement on the NEPR final report issued Sept. 21 2026, confirming earlier findings while noting inherited design flaws and corrective measures already taken.
Primera Hora reported on Thursday that LUMA Energy stated a tree branch and rodents caused the islandwide blackout on April 16 2025. Primera Hora reported. The Negociado de Energía de Puerto Rico (NEPR) issued its final report on Sept. 21 2026 adopting all conclusions from independent consultant Exponent Inc.
According to the new account the initial fault on the 230 kV line 50100 was cleared at the Manatí terminal but the Cambalache breaker failed due to rodent damage to the control cable. An aerial inspection five days prior had not detected the specific vegetation. The report attributes the cascade to inherited design deficiencies from the former Autoridad de Energía Eléctrica era that left no redundant controls.
Primera Hora reported that the NEPR recognized corrective actions already implemented by LUMA including redundant differential relays with independent power supplies distribution of trip circuits over two control cables relay replacements and other infrastructure upgrades. LUMA stated it continues investing in critical equipment and proactive inspections to improve reliability.
Initial fault and failed protection
The Negociado de Energía de Puerto Rico determined that the islandwide blackout of April 16, 2025 began at 12:38 p.m. when a tree near transmission line 50100, on the border between Barceloneta and Manatí, caused an electrical arc. Telemundo Puerto Rico reported. The initial fault was not isolated because a breaker at the Cambalache substation did not operate as designed.
According to the regulator's report, the cable that transmits signals to activate the breaker had been damaged by rodents inside a conduit. This prevented the protection systems from sending the necessary commands to disconnect the affected line. The design at Cambalache relied on a single cable for multiple safety functions, eliminating required redundancy. Telemundo Puerto Rico reported.
Also on PuertoRico.com: Puerto Rico power and water outages
Vegetation management and maintenance
El Nuevo Día reported that five days before the blackout LUMA Energy conducted an aerial patrol of line 50100 and failed to detect the vegetation concentration that triggered the event during Holy Week. The Negociado de Energía concluded that LUMA's preventive maintenance and inspection practices were insufficient to identify critical conditions in electrical equipment.
The regulator ordered the company to reinforce its inspection and maintenance protocols. The report also noted deficiencies in backup systems and vegetation management. Telemundo Puerto Rico reported.
Where the sources differ
All four outlets base their reporting on the same Negociado de Energía final report issued Sept. 21 2026. They agree on the April 16 2025 tree contact on line 50100 as the trigger, rodent damage to the Cambalache breaker control cable, the five-days-prior aerial patrol that missed the vegetation, and the order to improve maintenance. Primera Hora adds that the NEPR adopted conclusions from independent consultant Exponent Inc, that protection systems cleared the fault at Manatí, that the event resulted from decades of underinvestment and corrosion, and that LUMA has already implemented corrective measures addressing inherited design flaws from the AEE era. Metro Puerto Rico adds that the collapse occurred in under 20 seconds, notes deficiencies at Costa Sur and in communication channels, and states the NEPR requires LUMA to submit a public version of its own analysis. Earlier accounts from Telemundo and El Nuevo Día did not mention Exponent, the Manatí clearing, inherited design deficiencies, completed corrective actions, the under-20-second cascade, Costa Sur, communication channels or the public-analysis requirement.
What the reports do not say
The reports do not state the total duration of the blackout, the number of customers affected, the economic cost or whether any disciplinary measures were taken against LUMA executives. They also do not indicate when the ordered improvements to inspection protocols must be completed, whether independent verification of those changes is required, the exact scope of LUMA's already-completed corrective actions or the content of the public version of LUMA's analysis that must be submitted.
Sources
Every link below was opened and checked when this story was published and last updated. Official means a government body, agency or the organization itself; Reporting means a news outlet.
- Official Ratas contribuyeron al apagón general en Semana Santa del 2025, dice informe
- Reporting Ratas contribuyeron al apagón general en Semana Santa del 2025, dice informe
- Reporting Árboles y ratones: informe detalla causas de apagón general en Semana Santa de 2025
- Reporting Una rama de un árbol y ratones fueron los responsables del apagón de Semana Santa de 2025
- Reporting Árboles y ratones dejaron sin luz a Puerto Rico
How we checked this
Metro Puerto Rico, Primera Hora, El Nuevo Día and Telemundo Puerto Rico all reported on the same Negociado de Energía final report. Details about Exponent Inc conclusions, the under-20-second cascade, Costa Sur deficiencies, communication channels and the required public version of LUMA's analysis rest on single sources.
Compiled by the PuertoRico.com News Desk from the reports and statements listed above, and checked against them before publishing. It does not include original interviews. Spot an error? Email support@puertorico.com with a link to this story.