I don't know enough about electricity. Electrician told me I have 3 phase 400v and it wasn't common. Not sure what that means or what benefit it gives me.
It just means that you can run industrial gear; maybe was owned by a keen potter previously. Big kilns need 3 phase power. No it isn't common for domestic, but I have a few friends with big shed that have 3 phase power for machining tools.
Depending on what capacity the supply has; e.g. if you have a smallish 80A supply you can run a a good sized CNC mill in you shed.
Three phase is useful for industrial motors or if you need more than 200A service. If I wanted to add another car charger in my garage and use them at the same time, they would have had to bring in another phase.
Yeah, they all say that. And then when you try to claim it they have a million clauses in their fine print that allows them to weasel out of it.
Did you register to your equipment with them when you plugged it in? Do you still have your receipts? Did you use an extension cord anywhere in your power path at all? Did you know they only provide "current pro rata market value" for everything, which means their math makes all your computers worthless after they're a week old? Can you prove it was actually a power surge and not some other occurrence that took out your device? Etc., etc., etc.
Never trust your equipment to one of those guarantees.