external power panel light test A320
 

it seems that the external power panel light test on A320 is only possible on GPU ?
can anybody confirm or invalidate ?

External panel light what? Can I reach it from the cockpit? :}

the external power panel is the panel where the mechanic plugs himself for the push and engine start.
full of lights down there and a light test

Just making fun of your question, don't know the answer, sorry. :}

Works on APU as well, perhaps availability of AC power a factor. However - the test is not a part of factory A/C walkaround and is not a part of a "daily check" maintenance inspection either.

I am not sure about APU, with GPU connected (not required on bus) you can test all lights.With GPU disconnected only ADIRU/AEVC and ELT lights on(same for cold A/C).