Time Delay Relay: output = HIGH until triggered, then return HIGH after interval?
Use a 555 timer in monostable mode. This can be triggered with a push button on the leading edge. The output of the 555 should control a mosfet which supplies current to a normally closed relay (the 555 will not be able to drive the relay as it is). When the relay is activated it will open the contacts on the relay, disrupting the connected 120VAC. Note that the 555 timer, mosfet, and coil side of the relay will need to be powered by a separate DC source.







simulate this circuit &ndash; Schematic created using CircuitLab

Your relay doesn't need to be a SPDT, you can find a SPST that's normally closed. Also depending on the relay you can find, you may need to include a flyback diode. Use one of the many calculators online to find proper values for R1, R2 and C1.