Loud electric meter? An electricity meter makes a particularly loud humming noise at darkness. It...

An electricity meter makes a particularly loud humming noise at darkness. It is positioned within the communal nouns in a small block of flats and in attendance seems to be some sort of timer attached to the meter. Any design why it is making such a loud noise and what the timer is for; and what can be done?
My house is infested next to monkies, how...
Answers:    Try drumming the meter or timer, it may stop humming but will probably start again. Either or both could be humming, possibly a loose coil, maybe wishes fixed tighter to the backboard. The timer is for stair lights or door entry system.
Name my cactus?
Umm, do you have discount 7? In our block of flats when someone switches on a light within the communal hall path the timer whirs for 2 minutes until it switches off, so could it be the lighting? Ask your proprietor if you're renting.