Any electricians in the house?

This is a real puzzler...

...yesterday we lost a "circuit" in the house. I say "circuit" since the affected items are all over the place:

2nd floor - hall lights
1st floor - front hall lights, living room outlets, outside lights
basement - some overhead lights

...all no longer worky.

I checked the main panel, all breakers OK. To be sure I reset each breaker (off then on) several times, no help.

Next I checked each breaker to see exactly what was connected to it (since the legend printed on the panel was a little cryptic), in an attempt to determine which breaker is controlling the affected circuit. Each breaker was verified working properly (stuff went out and came back on as each breaker was toggled). After completing this exercise I still have no clue to which breaker(s) the affected circuit is linked to. FYI - My panel has no GFI breakers installed.

All house appliances are working normally...no dimmed lights or other weirdness. The house was built in 1973, has modern wiring and one panel box. In my past experience electrical issues were always pretty simple to solve, this one has me stumped.

What am I missing?

Call the power co, tell them you you may have lost a phase. Will the oven elements heat up?

Sounds like you lost one leg of your 220V in.

If you have a voltmeter and the knowledge to use it without getting thrown across the room, check for 220V at either a 220V outlet or inside the circuit breaker box.

If you did lose a leg, if you have any appliances like a electric hot water heater you will see some voltage on the dead leg causing untold head scratching and cursing. Damhik

And in the mean time unplug everything! This can damage electronics.

And cause a fire.

Try resetting the main breaker on your breaker box, one phase may have popped. Sometimes shutting them completely off than on again will do the trick. If that doesn't do it call the power Co NOW! Don't ask me how I know how much damage a gopher can cause when you have underground service!

Burned wire or bad connection to outlets?

You may be able to determine a dropped phase by looking at the circuits that don't work. A panel is set up so the phases alternate A/B/A/B/A... down each side. If every other circuit works, you do indeed have a dropped phase and it needs to get sorted ASAP.

It's not because I'm an electrician, but call an electrician

There is a possibility that there is a GFI receptacle in the circuit. They can be configured in such a way that everything downstream of the receptacle is protected by the GFI. This would not normally be done with the interior and exterior devices, but I have seen some goofy configurations in the past. You would simply have to reset the recptacle. Other than any obvious conditions, there could be loose connections(common with older aluminum wiring) that have burnt off in a junction box somewhere. These loose connections are the common cause of electrical fires.
Whatever you do, respect the voltage

First buy,or borrow a cheap voltage tester and check the outgoing side of each breaker. If you have 110 at all your single breakers, then test your double pole breakers for 220. A lot of people (electricians included) will use the quick wire plug in feature on outlets and switches ,that when overheated multiple times will allow the pushed in wire to either back out slightly ,or cause the spring brass that held tension on the conductor to lose it's grip. So it's possibly a circuit that starts out fine and goes to hell in a downstream plug or switch. Now the fun begins. Start at the first light or outlet not working,and closest proximity to your panel take it out of the wall and use your tester to check for voltage on both sides. It's a pain in the ass search for things like this,but if it's not a breaker,or a lost leg coming in (doubtful too many things working in the house) it's a good way to learn your house,and cheaper than hiring someone who will do the same.By the way,if you can find a non digital tester for this job you'll be happier with the results as digitals can give phantom voltage readings that will drive you nuts. Be careful,proceed slowly,and good luck.

My thoughts exactly! The Bozo that wired my house put the outside outlets, the garage, and the outlet over my water heater in my utility room all on the same GFI. It justs happens that my internet feed is in the utility room too, so when something pops the garage GFI, my internet goes out. He also wired all the bathrooms on one GFI, so when the powder room pops, I have to reset it on the opposite end of the house, in the master bathroom. Idiot...

The house must have burnt to the ground. No response from the OP.:eek1

Power Co was just here, both 120V phases and neutral checked out fine.

Turns out several of the affected circuits appear to be suffering from low voltage (~80-100) which explains why bulbs are not lighting up. Power co tech was of the opinion that perhaps the main panel breaker may be crapping out/acting flaky, electrician on call for tomorrow....

...never a dull minute....

Snap the main breaker on and then off a few times. Do it with a little vigor. Sometimes that will correct the problem for a short time, and let you know what the problem is. Sometimes the breaker won't stay on after, so be warned. Is it a Federal Pacific brand panel?

If you have the original 1973 electric service it's probably due to be replaced anyway.

Did anyone do any work on the system recently?

Replace a switch, light, outlet? If so, possibly a loose connection/broken wire.

The house was built in 1973. Hopefully it doesn't have aluminum wire in the walls. (some jurisdictions still allowed Aluminum wiring back then)

Tried resetting the main panel breaker several times before the power co arrived (some folks mentioned this technique can help restore a dropped phase) and behold the circuit did pop back to life for a few minutes....then keeled over.

No alum wire in the house, nor any recent electrical work performed.

I have a Cutler Hammer main panel, the main breaker is a C-H # CC2150 150A 2 pole 240VAC, looks like it has been there since Jesus was a baby. I am trying to imagine how a breaker would fail in this manner, I figured it would just die, not create weirdness like I am seeing...

A high resistance connection in the breaker would cause a voltage drop like that. The big danger is resistance = heat, enough heat can overcome the insulation and start an electrical fire in the panel.

...wouldn't the voltage drop due to high resistance be uniform throughout all circuits in the house?