The landlord pays for the electricity that powers the lightbulbs in the common areas. I have a sneaking suspicion that the landlord or one of the other tenants either 1) replace my working lightbulbs with non-working lightbulbs, and use my working lightbulbs elsewhere, or 2) shake my working lightbulbs hard enough to break them.

I often replace the lightbulbs in the common spaces, but they seem to go dead FAR more often than the lightbulbs inside our apartment. (granted, the wiring in this place is VERY sub-par, but the quality of the wiring should be similar in the common areas and inside individual apartments, right? Not significantly worse in the common areas?)

This is a log of my observations.

Log

Methodology

location	action	anti-counterfeit pattern?	bulb size/shape	glass type	wattage
3 Oct 2009
3F front stairwell	replaced, new	checkerboard	smaller (A15)	frosted	15W
1F rear stairwell	replaced, new	checkerboard	smaller (A15)	frosted	15W
2F rear stairwell	replaced, new	checkerboard	smaller (A15)	clear	40W
3F rear stairwell	confirmed still working	no	CFL	frosted	13W

A checkerboard pattern is a pattern that I draw onto the base with a permanent marker. "Checkerboard" means that every other thread is marked alternately black/clear. Also, the transition between black/clear/black is done at exactly the same place on each rotation, so when you look at that spot head-on, it looks like one column of a checkerboard. This is designed as an anti-counterfeit pattern. That is, it's something that someone else isn't likely to be motivated enough to reproduce.

Smaller bulb. I use an A15 bulb instead of the more normal A19 bulb, which means it has the same shape, but is slightly smaller. An easy way to tell the difference between A15's and A19's is to wrap my thumb and middle finger around the widest part of the bulb. If those two fingers can touch easily, then it's the smaller A15. If those two fingers have a ~1cm gap between them, then it's the larger A19.