I had a CFL light stop working in a fixture and was replacing it. If I tapped it, it would light for a second, so I thought it might be loose, but could not get reliable operation. So I replaced it.

When I put the old light bulb on a table, it came on full brightness! No connection to power. This seemed to last for several seconds before it finally went out.

What gives?

 

Where exactly were you when it lit by itself? If you were near a source of static electricity or other form of high voltage, it could have caused the gases within the tube to become excited and light. It is not difficult to light a CFL just by holding it in front of, say, a CRT television while it's switched on. Static electricity often appears at the front and is sometimes enough to light fluorescent bulbs.
Der Strom

 

Ahhh... I lied I said table, but meant stairs (was thinking stairs, but seeing table - don't ask!)

Stairs are covered with man-made material carpet, a great potential (pun intended) for static electricity.

That might have been it. It was strange, though.

 

It is certainly possible. Synthetic cloth (or synthetic fibers that make up a carpet) could easily hold a static charge, so it would make sense that the static discharged into the bulb.
Mystery solved?

 

Enough for me! Thanks

 

I would think an intermittently connected internal capacitor in the CFL may be a more likely candidate for the mysterious energy source. If not, you had better take pretty good antistatic precautions if doing any electronic work at home. That carpet must be quite something!