I have always used a serge protected extension lead for my embroidery machine. Earlier this year I was in the builders merchants for my husband and saw extension leads that guaranteed to cover what ever was on the cable for up to £1000 which is $1345.86 (as I write). This got me thinking and the shop kindly went through the leads they had to see if there was a greater monetary value of goods covered. Last week I was with our elder daughter and in killing time waiting for her I discovered serge protected extension leads that will cover up to £30,000. I have just received one of these extension leads and will use it with my embroidery machine for extra peace of mind.
When I bought my Husqvarna over 10 years ago Maarten from Thorpes advised me to buy a Belkin Surge cube, so I've used it ever since.
We've had a few black outs here in Newcastle, but nothing that has damaged my sewing machine and I, like Karen, unplug my machine when not in use. Love Chris
But this protection doesn't cover external surges from the power substation so I have always purchased the best surge protection power boards available, ones with an Insurance Cover Guarantee.
Having worked the computer industry my choice has always been APC, more expensive to buy, but not $10,000 (the cost of my dearest machine)
I have added a little article from C-Net, that may be of some interest
https://www.cnet.com/news/9-things-you-should-know-about-surge-protectors/