Everything becomes a fuse at 10,000 amps

Some details about the Los Alamos townsite power outage on May 8.

Boomtown sat down with Dennis Astley, the deputy utilities manager for Los Alamos County, to learn more about the townsite power outage that happened in early May. Here’s what he told us.

Linemen from the Los Alamos Department of Public Utilities working to locate the failed underground cable near the Los Alamos Aquatic center on May 11, 2026.

What happened?

A 13,200-volt underground electrical distribution cable near the Aquatic Center failed, and the resulting arc burned through the adjacent conduit and cables and caused a massive power surge on that circuit. The monitoring equipment at LANL’s substation, which supplies the townsite, measured this surge around 10,000 amps; the typical current through these lines is 50 or 100 amps.

Journeyman Lineman James Suazo unearths the fault (left). The 13,200-volt distribution cable, which feeds downtown Los Alamos, arced and burned the adjacent cable resulting in a massive power surge through the entire townsite grid.

Why did the entire townsite lose power?

The initial surge went right through the circuit breaker for the downtown circuit and tripped the main breaker at the substation that supplies all six circuits that power the townsite. LADPU engineers are still trying to understand what happened with the protection relays that should have opened and isolated it to the one circuit instead of all six.

That surge also burned wires on two overhead poles along Trinity Drive, which were on the same downtown circuit. There was also an underground fault in a different circuit on North Mesa.

Journeyman Lineman Wayne Valdez preparing the end of the replacement section of cable.

What caused the cable to fail in the first place?

Crews have no idea. It’s a kind of cable that has not historically failed. It could have been a minor flaw in the manufacturing that took time to appear. It could have been a tree root. But there was nothing left to indicate what caused the failure.

Supervisor Timo Martinez (center) and Journeyman Linemen Josh Rodriguez (left) splice one end of the replacement section of cable.

Was this a freak event?

When you have a substation with the capacity that serves Los Alamos, you can have incredible fault currents, and with this size conductor [500 mcm], it moves a lot of power. It was 10,000 amps on a wire that’s rated for 130-140 amps. The wire became a fuse. Everything becomes a fuse at 10,000 amps, and it did nasty stuff. But it is rare to have something of this magnitude.

Journeyman lineman Roland Rodriguez (left) and Supervisor Jonathan Garcia confirming the distribution circuit is operating normally after replacing the failed cable.

Editor’s note: This interview was condensed and edited for clarity.