I started the simple task of replacing a bathroom light fiixure. In the process I decided to finally label all the switches in the circuit box. I turned them all off and on, except for the master switch and documented my findings. The problem is that none of the switches turned off the bathroom light fixture.
I saw something like this (in a public school yet) one time. A wire was connected right to the bus, presumably because all the breakers spaces were occupied. Plus, of course, because someone was stupid. To the OP, something like this may have been done in your house. If you are not comfortable opening your panel or don't really know what you are doing, then hire someone. Let us know what you find out. BTW, I assume you are in a single dwelling, not an apartment or something?
I am in a 2 story house. There were 7 switches which I could not find what they controlled. I presume some were a/c outlets, but I was only checking for lights or lights plugged into a/c outlets. My son, the light checker (I was in the basement), identified 3 different lighted areas that never went off after I individually switched each breaker.
It is not uncommon for a breaker contact to "weld" itself closed. It could be that this has happened to you. If so, the breaker handle can move to the off position but the breaker contacts won't budge. Or, you could have a sub-panel between your main panel and the load. Or, if you are only turning off the single-pole units, it could be tied to a 2 pole. Or, there could be some cross-wiring between two breakers. Try turning off all the breakers except the main, and then turn them on one at a time until that load is energized. Then, leave off the breaker that you have identified, and hunt through the rest to see if any other breakers will operate that load. If so, then you have a load tied to 2 breakers. Tere can be other things causing this problem, but I think these are the most likely. Let us know how it comes out.
there is a low cost gizmo that you can buy. its a 2 piece tracer. one piece plugs into an outlet and generates an RF signal. the other is a unit that you slide up and down the breaker panel. it lets you locate which breaker is on the circuit.
i have one. it kinda sorta works sometimes. mine is similar to this
Did you switch each breaker off, one at a time? Or did you turn them all off and then turn them on, one at a time? Its possible that someone screwed up and fed one branch circuit from two ends (two circuit breakers on the same leg). Try the latter method and see what happens.