https://www.sunsolarelectrical.ca/blog/why-are-my-lights-flickering-at-home/
from link:
Circuit Overload
Do your lights sometimes start flickering when you turn on an appliance, such as your dishwasher or microwave? If so, then you might have an overloaded circuit, due to the larger amounts of electrical current which these appliances draw as they startup.
Infrequent, brief flickering is usually not serious, but if you find that the problem occurs all the time or lasts more than a few seconds, you may need to upgrade or install new electrical circuits in these areas.
Voltage Change
Though your home’s electrical voltage can fluctuate slightly, it should always fall within the range of 115 to 125 volts. Voltage change outside this range is problematic and should be diagnosed by a professional electrician.
Signs of severe voltage fluctuation include:
lights flickering or dimming when you switch on large appliances
flickering continues even after you have turned the appliance off
light fixtures dim at unexpected times
light bulbs burn out more quickly than normal
appliances or electronics shutting off or malfunctioning
Loose Wiring
Is your light flicker problem getting steadily worse — for no apparent reason? Loose wiring could be at fault, whether it is due to wear and tear, outdated wiring, or incorrect installation. This is an electrical problem that you must take very seriously.
A loose connection anywhere within the system is a fire hazard, as it is liable to cause arcing or overheating. Don’t risk a devastating electrical fire or complete loss of power in your home – call for electrical service as quickly as possible.
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Possible fire hazard...
If your neutral connection to the transformer on the pole loses connection, your home appliances could find themselves being powered by voltages approaching 240 volts instead of 120 volts. You can lose a lot of appliances in a hurry if this happens. Happened to a friend.
Even just a loose connection could cause some of your appliances to experience damaging voltages.
We did have an electrician, two,actually, (we had by beother’s elecricisn friend come over and check,too) check it out, and say they weren’t concerned because they couldn’t find anything obvious. Themone electrician tried to,say the light bulbs were causing the issue, but id be surprisedmifmthat were really the case.
The problem does resolve when the appliance if off (ie the washer machine seems to be the big issue).
The problem hasn’t really gotten worse, it just started happening about a year ago. We are gonna cal.,another electrician thiugh before we call,the power company. We didn’t really,tell the last electrician that the issue is so bad that it kicks off the computer, and I have to restart the bac,up,power box because it won’t quit beeping until we do.
I am concerned about loose wiring, but the fella stated that he woild,have detected it. I dunno much about these things. Just going by what they said, but yeah, we are gonna get a other opinion right off quick.