Question about old house electrical wiring

The house I just bought is 65 years old, and has original wiring through most of the house. I just installed a new ceiling fan (replacing an old light fixture) in one room yesterday, and suddenly three of the ceiling lights on that same circuit, BUT NOT ALL, stopped working. The wall outlet on that circuit still works.

What could be happening? The old wire is really discolored, so I may have swapped neutral and hot, but that’s the only thing I might have changed. I used the same two leads that were feeding the previous light to hook up the new fan, and the fan works fine.

Loose connection in one of the boxes you were in. Is the wiring solid or stranded.
Did you replace the ceiling box with a fan box?

Likely something was knocked loose and the three lights are downstream from your fan’s box. This is not a good thing. You may be able to find and reconnect the splices properly if you take down the fan. If you can’t fix it, seek professional assistance.

I was only in one box, and I was very careful to only undo and reuse the same two wires that were connected to the previous light. The wiring is solid, not stranded. The original ceiling boxes are all reinforced to the ceiling joists.

Unless it seems clear from the responses that I probably reversed hot and neutral on the fan, I’m not going to take it back down. I am otherwise going to just wallfish a new piece of Romex from the attic to the basement and feed those three lights off of that. There’s way too much stuff on that circuit anyway, and I’be got a basement circuit that has almost nothing on it that I can splice into.

from your description there might be wires connected in that ceiling box that power the nonfunctioning lights. the fan might be a splice off that. either way, if in going into that box then you might have disrupted the splice connection, this can happen with poor condition wiring (either due to age or original workmanship); a push or a tug might be enough in a bad case.

redo all connections in that box. label the wires before unconnecting to aid in proper reconnection.

Were there only two wires in the box you were accessing? If there were other wires, it’s all but certain that a splice came undone, and could be a hazard if it isn’t fixed.

Let me get this straight. Your wiring is 65 years old & crusty? You could not tell which of the two wires (not three so no ground), was the neutral? You may have that ceiling fan wired incorrectly? You have either no connection or a loose connection to three other lights? You do not know which one you have. BTW, Loose connections usually get hot & are a major source of electrical house fires.

Now you want to leave this mess in place and add a new wire from the basement panel to power these three lights. The new wire is a good idea, as is the separate circuit. However, if you leave the rest of the wiring as is, you could get a cross feed from the new circuit to the old circuit. This could be very dangerous as you will need to switch off both of the circuit breakers to assure that any of the fixtures or wiring in either circuit is safe to work on when needed. Will you remember to do this twenty years from now? How will the new owners know to do this? Checking the circuit with a meter would not assure safety, as this may be a loose connection that sometimes flows electricity and sometimes does not. You could electrocute yourself, or someone else!

Your best fix is to hire a certified electrician to do a compete upgrade on your entire house wiring, including the circuit breaker panel. If you do the work yourself, please replace all of the wiring for these three lights. Be sure to disconnect them from the ceiling fan circuit, & pull all of the old wiring physically out of the walls. This helps to avoid confusion in the future as well as assuring that you will have no cross-feeding going on. With the old wires gone, they can not conduct electricity, nor can they start fires!

IHTH, 48.

This sounds like a really good way to end up with up to three light fixtures, or some other piece you don’t yet know to be affected, that are sometimes 120v, and sometimes(briefly) 240v–assuming a loose/intermittent connection.

One of the most vexing things about working with old wiring, particularly 14ga. copper is that it is frequently overloaded as demands increased beyond the vision of the original designer. Over time, the overload makes the copper brittle and it’s a pain in the ass to work with because it tends to break instead of bend. Sometimes all it takes is a bump, not even a twist or bend, to get the stuff to snap.

It’s not aluminum wire, is it? The age of the house makes me wonder.

if the wire is discolored at the ends in a 65 year old house then it may be overloaded or bad connections (this easily with aluminum wire).

I’m going to isolate those three light fixtures by cutting the connection to the other circuit. That won’t be hard, all I have to do is take down one small light to get at the connection.

The wire is copper, I don’t think they were using aluminum in the early 50s much.

Maybe don’t take the fan down, but you have to rewire it. You have solid evidence, in the form of previously working circuits now failing, that the fan was wired incorrectly. For all you know there are bare wires with voltage on them behind that fan that could touch wood or insulation with potentially life threatening consequences.

Or better yet, have an electrician do it. Paying to have a ceiling fan installed will not break the bank, but it just might prevent a house fire.