On a particularly cold November evening, power demands for heating, lighting, and cooking were pushing the electrical system to near its peak capacity. Transmission lines heading into southern Ontario were heavily loaded. The safety relay had been misprogrammed, and it did what it had been asked to do: to disconnect under the loads it perceived. As a result, at 5:16 p.m. Eastern Time, a small variation of power originating from the Robert Moses generating plant in Lewiston, New York caused the relay to trip, disabling a main power line heading into Southern Ontario. Instantly, the power that was flowing on the tripped line transferred to the other lines, causing them to become overloaded. Their own protective relays, which are also designed to protect the lines from overload, tripped, isolating Beck Station from all of southern Ontario.