Where: The lavatory of a midsized apartment in the center of St. Petersburg, next to Haymarket Square. Three families live in the apartment.

What: Three naked bulbs on the wall of the lavatory. Each of the three families living in the apartment has their own bulb. Outside by the lavatory door are three switches. Wires lead from there to electric meters; each family has a meter. This kind of system in a public space assumes that expenses for lighting are not shared, but accounted for by each family's electric meter. There are three bulbs in the hall, and three in the kitchen.

Using somebody else's bulb is a serious violation that can result in a nasty argument. The violators frequently enough turn out to be visitors who may not know which switch belongs to their friends.

Separate bulbs are primarily a feature of midsized apartments, where there are comparatively few families (no more than six or eight). You rarely see this anymore. Even in apartments that used to have the same number of bulbs as they had families, only one bulb is used and the expenses are shared.