A sensor to detect if a device is powered on?

[Bry (Bryan)]

@Bampa

I want to get a remote alarm (iPhone) when my oil burner

Crossposted.

Detecting 120V power ON and sending an alarm to my phone via SmartThings

I want to get a remote alarm when my oil burner stops working for any reason, other than being switched off. When an unexpected glitch stops the oil burner, so 120V power comes onto the reset button switch light. I want to be able to connect to that light, detect when it is ON (burner is OFF), and get an alarm message via SmartThings. What ST device can I connect in parallel to that light that will connect via my home WiFi to the ST hub to send me an alarm? Thanx, Ray