One Manhattan power room took down FAA air traffic control in 1991

> Because the alarm wire carried current only during a fault, an open 25-inch strap produced the same electrical state at the receiving end as a healthy power plant.

I’m a building automation and controls tech in Manhattan, and for this exact reason digital feedback points and alarms are always normally-closed, and analog points are 4-20mA. This allows differentiation between nominal zero values and a fault in the loop.

Disasters like this are what our best practices are borne from.

20 years ago some friends and I were walking by 33 Thomas St and discussed how that must be the building that they imprison Magneto in. Weird looking building.

The overall site has a cozy feel to it. Well done

This is an awesomely clear and methodical explanation of system failure.

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