In the airbus overhead panel (320) regarding pushbuttons that have off /fault LED, which position causes the OFF light come on. I.e. does OFF appear when you push in the button or release the button ?

l am not an Airbus expert, so somebody else may have to correct me on this. But l believe that the 320 uses a ''dark cockpit'' concept, meaning if a switch is in its normal flight position, it is not lit up. This means that some lights will illuminate ''off'' and others might illuminate ''on depending on what is normal (or not normal, if it is illuminated) for flight. This way, if every switch is in its normal position, nothing will be illuminated if you look up.

The first guy is correct.if the button is not in the correct position either in or out the off light will illuminate.

The button can be in either position in or out. If the system sees a fault within the system you will get a fault light. Then you have to determine the reason. It gets a little complex from here but if you are in the aircraft and can see look at the screens you can figure it out real quick.

the normal switch position is depressed meaning ''on'' as aircraft is powered electrically it will be powered right away if there is a corresponding fault it will be illuminated ''amber'' to switch the system or reset the system u have to push it a white light appears indicating system is off. The sw. position now is undepressed.
Examples of system that has these switches are: generators switches (gen 1 & gen 2) Probe heating & window heating this one awaiting either eng 1 or eng 2 powered or running.