WMATA Car Maintenance Question

After 20+ years something I've noticed more & more recently is a series of car lights cycling off only in the lead car on some, actually majority of trains right after being keyed up. I finally remembered to grab a photo - anyone in CMNT might know what this is. (If you want to remain anonymous PM me)

The operators do this to reduce glare produced from light leaking through the cab partition glass (railfan window).

A modification was approved to add additional tint to the partition glass but I don't think this project has been funded.

Thanks - So they are throwing the car lights c/b for either circuit A or B if I'm recalling my info correct.

Does it really matter which one as I notice the light over the "railfan" seat is always off regardless of sequence of car lights out.

Each car regardless of series has two main lighting circuits plus the emergency circuit which powers the lamps over the doors. The actual layout of the circuits varies by series but they always shut off the circuit that feeds the fixture directly over the windows.