Researchers at the Massachusetts Institute of Technology (MIT) have developed a system that determines exactly how much power is being used by every appliance, lighting fixture, and device in a home.

To enable the MIT technology, no wires need to be disconnected. The placement of the postage-stamp-sized sensors over the incoming power line does not require any particular precision.

Because the system samples data very quickly, the sensors can pick up enough detailed information about voltage spikes and patterns. Dedicated software supports the differentiation between every different kind of light, motor, and other device in the home, showing exactly which ones go on and off, and at what times.

One installation at a military base used for training exercises revealed that large tents were being heated all day during winter months, even though they were unoccupied for most of the daytime hours — a significant waste of money and fuel. Another test installation, in a home, found an anomalous voltage pattern that revealed a wiring flaw; the defect had caused some copper plumbing pipes to carry a potentially dangerous live voltage.

The MIT team used an array of five sensors, each slightly offset from the others, and a calibration system that tracks the readings from each sensor and calculates which one is positioned to give the strongest signal.

An interface allows users to “zoom in” on specific time segments, revealing enough data to tell specific actions, such as when a refrigerator or water heater turns on or off.

According to the team, the system, once developed into a commercial product, should only about $25 to $30 per home.

“We’re trying to lower the barriers to installation,” said MIT researcher John Donnal. “It just goes on with a zip tie.”


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