Airbus Annunciator light test
Giday all, just a quick question about a small piece of airbus trivia ...
The A330 has a switch in the roof for annunciator light test - switch it up and every light in every panel comes on.
My current and previous airline both profess to follow standard Airbus SOP - but I have never seen a checklist reference to when you are supposed to use that switch, or an ECAM procedure that requires its' use.
I know a lot of people just switch it on anyway on first-flight-of-day and test the lights, makes sense from an airmanship point of view, but strange that it's completely absent from the SOP. So why is that switch there and when are we supposed to use it?