Intertherm electric furnace model EZEB-012HA won't shut off with thermostat in off keeps running have to throw the main braker on panel

You either have a stuck relay or shorted thermostat wiring. Easiest thing for you to do is disconnect the thermostat wiring at the furnace. If the furnace then shuts off, you have a short in the wiring or a bad thermostat.

Sounds to me that your heater sequencer, may be stuck. Look inside the electric heater box , inside furnace , where all the wires go that hook up the heater. There is a sequencer relay that has 6 to 8 wirer on it . Turn power off tap on it . Then it may work , if so you are going to replace that control. Hopefully this was helpful.