Do You Need an Uninterruptible Power Supply in Your Home?

Power outages in individual locations are variable. The situation in any home office should be assessed based on local information. However, for a general rule, industry sources provide some rough estimates for North America. It is thought there may be approximately 15 power outages a year that are enough to cause a problem for computers in offices. Most outages last less than five minutes. Overall total time of lost power during a year is approximately one hour and 40 minutes. [Source: http://www.crawfordtech.co.nz/datasheets/PoE_inside_or_out.pdf ]

Looking at these numbers in terms of running a home business where the computer probably is not running 24/7/365, each owner might make an informed estimate about the cost/benefit ratio of a UPS. For example, let’s say you are working and on the Internet from 9:00 AM to 5:00 PM. Although most home office workers I know are not this structured—I am just as likely to be working at 7:00 PM as at 7:00 AM, a little thought experiment works better with a specific example.

In this situation, you would like stable computer use for a total of eight hours (480 minutes) a day, allowing one hour off the PC for lunch. Assuming a five-day workweek and two weeks annual vacation, this adds up 120,000 minutes with a live computer a year. Using 100 minutes per year as average total outage,seems to suggest the likelihood of a power failure during work hours is less than 0.08%, or less than one chance in 1,000. So why spend several hundred dollars or more on a UPS?

Suppose you are in the midst of compiling a lengthy report for a client that will earn you $1,000. You make backups on the PC as you write, of course. If you are really cautious you also make frequent backups to an external source, although many people don’t go this extra step until the project is finished. O’Toole’s commentary on Murphy’s Law (“Murphy was an optimist”) is operative. The power fails. Not only is there no UPS but an important feature of a UPS system—an automatic shut down including file closing is missing as well. When the system comes back on, you find file corruption because of the hard disk caching system, where current information was written to memory and not out to the disk. Even the previously saved material now seems garbled.

How does that $300 UPS outlay compare to perhaps recreating a $1,000 project? Buying a UPS may begin to look like a legitimate business deduction if for no other reason than as a form of insurance. Choosing the right size UPS takes some thought and calculations.

The next article in this series will go over sizing of a UPS for the home office.