The International Energy Agency (IEA) and others have estimated that the average age of power transformers associated with the national US grid supplying electricity to all of the US exceeds 30 years, many closer to 40 years.  Several things have happened to these transformers during this period.  Average loading, and hence heating, has increased significantly.  All of the older transformers used a combination of “old-style” grain oriented electrical steel for the core, more prone to heating than current high efficiency grain oriented electrical steels, and an “old style” transformer oil, which is much more prone to breakdown and ignition than current transformer oils.

The situation is further compounded by the rapidly expanding demand for electric power from the grid due to the increase in data centers, EV charging, and connection of renewable energy sources.  To add to the fire, pun intended, most utilities do not carry or have access to spare transformers.

If there is a lesson to be learned from the fire this month at the Heathrow airport, it’s that we shouldn’t assume that the grid is OK.  We recommend a dual phase re-inspection of grid transformers and the establishment of a strategic stockpile of critical transformers.  Ignoring the vulnerability of aging transformers on the US electrical grid is not smart management.  Disasters happen.  Planning to prevent predictable disasters is simply execution of common sense.