way back when, I worked for a VHS dubbing facility where we had a voltage meter with an alarm set to warn when voltage would drop below a certain rate, but I don't remember the exact value. At that point, the VCRs would glitch and the recordings would be bad but the dip would be momentary and not enough to force the machines to stop like a full outage. When the alarm sounded, we stop all of the decks and re-rack the room and restart all of them. Without the alarm, it was impossible to catch these without 100% QC of a tape. That is when I groked how much worse a dip can be than a spike. Some equipment will start to pull harder when the voltage drops which kills more power supplies than spikes. Surge protectors are great for the spikes, but line conditioners or battery backups are the only protection from the dips. Management decided that the fully time battery conditioned expense was not worth it, so we were constantly running with some set of equipment down because of a dead power supply