At times my thermostat in another room, oven, clothes washer, dishwasher, and two outlets in the kitchen go out for no apparent reason. The breakers don't trip. The GFI receptacle doesnt trip. We have a coffee pot plugged into one outlet, and humidifier plugged into the other. An electrician was out when the power came back on and could not figure out why the power goes out. He said he would have to see it when the power was out.
With both 240 and 120v devices having a problem I would first call the power company and report the problem to them. Usually they will preform a service safety inspection for free (they don’t want a fire in their gear). Then I would check the type of panel there 2 brands known to have these problems the first is federal pacific (FPE) the stablock model of breaker is known to fail (to the point I will only remove them). The other is zinsco , I haven’t seen the extent of problem on these but others have reported.
If neither of these brands one thing I will do is turn all the small breakers off, then cycle the main breaker on and off 10-20 times. This cycling the main breaker can clean carbon off the hammers in the breakers and reseat them For a temporary fix.
If you feel comfortable remove the dead face or front cover from the panel and look at the main feeds looking for overheating damage (I would expect your electrician at least did this).
Providing us with a photo of the panel and model number we may come up with additional possibilities if the utility comes up with nothing, but most of these failures I have seen have been on the utility side other than a few main breaker problems or rule of 6 “main” for the lower section.
A circuit is defined as a circuit breaker (often a double breaker with tied handles) and all the outlets and hardwired devices that it controls, i.e. that lose power if you switch it off.
Obviously, some circuits are failing, and whole circuits are failing at the same time (that is, all the outlets/devices on the circuit at once).
So I need you to identify the failing ones. Often if your panel is properly labeled as required by law, this won't be too hard.
Cut up some Post-It notes to make flags, and stick the flags on the breakers that are failing. Then, shoot us a photo of the panel face. Also if possible the label that describes the make/model/instructions of the panel, and the breaker labeling chart if any.
Do this before you call in an electrician. This may be free to fix.
What I want to see is if all the failing breakers fall into a pattern that looks
For most panels, every other row, like in this answer
All on the left side or all on the right side for Pushmatic.
On a Zinsco, could be anything, so, not helpful.
If it does follow this pattern, then this is almost certainly a power outage from the power company. This is what power outages look like. "Why doesn't the power fail completely? Because in North America, power is delivered as 3 wires. Typically 1 wire fails. 2/3 chance it knocks out half your panel. 1/3 chance it causes a floating neutral which makes your voltages go bananas.
Did the Utility actually open your meter and check the connections? A thing that has been happening a lot lately is that when they come out and plug in the new "smart" meters, the act of unplugging the old electro-mechanical meter and plugging in the new one exposes some previously minor corrosion or spring tension weaknesses that then become worse with the new meter. I've seen it 3 times in the last year. The symptoms leading up to the discoveries were exactly as you described in all 3 cases.
Everything you are describing points toward a bad 120v leg on your 240v single phase service. Most likely up at the pole, mast, or at the service panel. Either way you will need to call your utility company to come check it for you and visually inspect all those connections and perhaps do a load test.
If every 240v device goes out but some 120v circuits still work then its almost always a bad connection at the service or pole on one leg of power. this is why NONE of the 240v circuits work... because none of them are getting both legs of power.