My UPS starts making a rather loud noise (which sounds a bit like a very loud version of a fridge's motor) when I turn on the oven. It's also vibrating quite a bit when that happens.
It's the only electric appliance in the house that has this effect on the UPS. Everything else, including the water heater, doesn't affect it.
Changing to another wall socket (I've tried one that is controlled by a different safety switch and therefore should be on a different circuit) doesn't help.
Why is this happening? But more importantly, can this actually damage the UPS?