Check your UPS power connections!

Check your UPS power connections to make sure the proper devices are on "BATTERY BACKUP" outlets and not "SURGE ONLY".

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I generally advise everyone use a UPS (Uninterruptable Power Supply) on their computer to help prevent data loss due to power line disturbances. Recently however, a friend who had taken that advise, started having trouble with disk errors on an external 1 TB USB hard disk. The disk was used to hold nightly backups so errors of any sort were a big worry. Initially, I thought it might be a bad disk, but after running a disk check and fixing errors I determined that the original disk was just fine. I was still concerned however and examined the setup closer. I discovered that the problem was most likely the result of the drive being improperly connected to the UPS. This lead to power failures that resulted in errors on the disk. The user hadn’t noticed the power failures on the backup drive since the computer and the rest of the system were properly connected to the UPS and operated through the power outages.

If you examine the outlets on most UPS units you will find that some are labeled “BATTERY BACKUP” and others as “SURGE ONLY”. While the meaning of these labels would be clear to anyone, it turns out that my friend had poor close up vision and couldn’t read the relatively small label above each column of outlets. He also neglected to read the manual and therefore was unaware that there was a difference between the outlets and assumed that all of them were providing battery backup functionality when in fact only about half of them were doing so. As a result of this incident, I’m recommending that all of you check your power connections to your UPS and make sure that you’ve got the proper devices on “BATTERY BACKUP”.

By now, I’m guessing that many of you just discovered you don’t have enough outlets labeled “BATTERY BACKUP”! What to do? First, realize that not everything needs to have a battery backup and some things can live just fine on a “SURGE ONLY” outlet. The order of importance is roughly like this:


  • Computers
  • External Disk Drives
  • External CD/DVD Drives


  • Monitors
  • Routers
  • DSL / Cable Modems


  • Printers
  • Scanners
  • Everything else

If you want to get maximum run time on your battery I recommend only putting the minimum configuration on the “BATTERY BACKUP” ports. Your needs may be different but realize everything that continues to run when the power goes out will shorten your runtime.

If you’ve not already purchased a UPS for your computer, I highly recommend that you consider making a UPS your next computer related purchase. Trust me, it will save you a lot of time and frustration later when the inevitable power failure finally happens!


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