dcarch, in her first pics she did produce a photo of the ballast wiring diagram. On it the black wire went directly to the ballast as she now states. On the ballast wiring diagram again they show one wire from each lamp joining together and then connected to the incoming neutral wire. Not the way I find most ballasts. All of the ballasts I work with take the incoming wires and connect directly to the ballast with a ground wire, bare usually just connected to the fixture for safety reasons. Until I had a clearer picture I hesitated to say more although I am sure the white wire does not connect to the fixture. jrrr, on your pic of the ballast above, I assume the thicker black wire is the incoming power cord? And the one black wire of this is wire nutted (the clear connector) and then goes to the ballast. What does the other black wire of this incoming power cord connect to? It appears that this 2nd wire is wire nutted (another clear connector) to the white wire that is loose in your first picture? Referring back to the first wiring diagram on your ballast I would say that the white wire in question came out of one of the holes next to the white wire that loops from each plastic end piece in your first pic. That would follow the diagram on the ballast as they are using the end plastic piece as a connector. If foreign companies had quality control departments like we used to have here, that fixture and any else produced by that line would be scrapped or at least inspected individually before shipping. But that was a long long time ago on a planet far far away. I would return the fixture if that loose white wire won't slip into the hole next to one of the white wire loop. Once in you should not be able to pull it back out easily but since it is 'hot' when the fixture is plugged in I would not want it to be a loose connection. That could spark and soon melt the plastice end piece of the lite tube. Hope this makes sense. If you post any more pics, pull some of the same color wires out a bit so they photo individually. Won't hurt any thing and you can test the fixture without the cover plate on. Once you insert that white wire of course.

Ignoring the ground wires(since you know where they go) I can't be any clearer than this. You have two terminals(the part where you push the wire in next to the screw terminal is the same terminal, maybe that is your sticking point?) on the old switch. Let's call them line and load. The line terminal is the one with the 'mystery' wire. The load terminal is the other one. Take All the wires on the load side, marrette them to the load Side wire on your new device. Take the wire from the other terminal, marrette it to the other wire on the new device. Ta-da!

Well the mystery wire remains a mystery. I had my dad (who is an electrician) look at it today. He said there is a short in the wire. Even more strange, it is interior wire running outside. There is a city sewer manhole cover in my yard on the side of the house with the wire. And low and behold inside the pit is an electrical wire with a rusted receptacle box on the end. But it has underground wire. So maybe there is a splice somewhere that went bad. There is no power at the receptacle. Why would there be a receptacle inside the sewer? I think it's a storm sewer, not a sanity sewer. I don't know. I was thinking maybe it's for Christmas lights but that's a lot of work to run the electric. And there is a 2" pipe towards the top of the pit that looks like it could have been for a sump pump. Makes me wonder where it would be pumping to. I'm intrigued. I want to know what it is. I may see if the city can shed any light on it but it probably isn't worth their time.

It could be several things. Metal conduit serves as the equipment ground, so there wouldn't be a separate grounding conductor but that presumes that the metal conduit goes all the way back to the service panel and isn't just for physical protection. Is the rest of the house wired with metal conduit or can you see the metal conduit at the service panel? A multi-wire branch circuit, the two hots (red and black) share the neutral. There are some rules for a MWBC that must be followed. A 120/240 volt circuit that would most commonly be used for household appliances like ranges and dryers. An improperly wired 240v circuit. There's a fair number of amateur electricians who believe that a 240v circuit requires a neutral and wire it incorrectly. Are the wires just hanging in space as shown in the picture? Have you figured out which breakers control that circuit and what do things look like at the panel?