The present invention in situ reconfigures connections within an electric circuit, such that a previously open circuit becomes a permanent in situ electrical pathway. A heat-activated electrical coupling comprises a heat-activated coupler and a heater. The heat-activated coupler comprises a preform of a material that changes a physical or electrical state in response to heat from the heater to bridge a gap between separate but adjacent ends of respective circuit traces. An in situ reconfigurable circuit comprises the heat-activated electrical coupling, a fusible link, a primary circuit and a secondary or back-up circuit. An in situ recoverable electrostatic discharge (ESD) circuit comprises the heat-activated electrical coupling, a primary ESD protection portion, and a secondary or back-up ESD protection portion. A method of in situ reconfiguring a circuit comprises creating the heat-activated electrical coupling and activating the electrical coupling with heat.