Such 'brown outs" can be very damaging to some electrical equipment. I believe our electrical utility can even be liable for damage caused by such situations, depending on the root cause of the failure.
Sadly, I'm willing to bet that their failure to say things like that means that if they print something like that, it opens then up to some type of liability. One thing you can depend on- big business covers it's hiney at ANY cost, particularly if that cost will end up paid for by the customer and not themselves...As I said most states have a PUC (public utilities commission) that the utilities must work with on things like rate increases and liability of damage of customers property due to utility caused problems. There was a recent natural gas pipeline explosion that damaged dozens of homes in San Bruno last year that will end up costing the utilities hundreds of millions of dollars and the PUC will make that it comes out of the utilities cost of business not just passed on to the rate payers, at least in theory anyway.Makes you think of building a cutout circuit-- much better to hard fail across the board than what happens to all those poor 'tronics.. testament to some decent engineering, really, in my mind- tolerating power fluctations of that scale is impressive!At the refinery I worked at before retiring we had all sorts of protection relays at all the substations on our property to trip power off if over or under voltage or frequency. Power outages are and were expensive but not as expensive if many large industrial motors were to burn out, some were of the tens of thousands of horsepower. I've seen a 240v AC on two different breakers- breakers that were NEITHER tandem or dedicated to the AC unit, a hundred thousand BTU through wall job.. Also on one of the circuits was all of the exterior (mostly non waterproofed, none GCFI) lighting and sockets. Guy asked me if I could figure out why he blew out three air conditioners in five years. Surprised it took that long. He told me the ONE breaker would trip and the AC would make "funny sounds" until he went and flipped the breaker back. Gee..
Any chance you have busted ground some where? Similar symptons were seen at my inlaws after a lightning strike, turns out their ground wire had been bruned out.
Blessfully Nick is in AU and doesn't have a neutral return in the same context as we do here in the USA.
Therefore, something goes wrong in the USA, we going down too here in Canada.
Things are back to normal now, so I don't think it is anything in-house. We actually have 3-phase power, and I could see from the meter that phase 3 had gone (at least the LED was off) then phase 2, then phase 3 again. So in our case it's possible for some parts of the house to work OK and others not.