Planning to write about surge suppression for a long time, I've been reading as much as possible from many sources online. It's a topic people ask about frequently, and one that needs to be addressed more often than when you set up your first computer.
There is a surprising amount of debate about surge suppression, and real facts are hard to find. Debate aside, most agree that some level of surge suppression is absolutely necessary. I am not an electrical engineer, but I'll tell you what I've read and continue to recommend and use good surge suppression.
A good place to start (though some disagree) is the How Stuff Works web site. This is a long, informative article, well worth the time to read.
Harris, Tom. "How Surge Protectors Work." 05 January 2001. HowStuffWorks.com. <http://electronics.howstuffworks.com/surge-protector.htm> 14 October 2009.
There is are differences between a surge suppressor, a surge protector (not possible) and a uninterruptible power supply (UPS). The best protection is a whole-house surge suppressor. They're not expensive, and you should have a chat with your electrician about having one installed.
Nothing will protect your equipment against nearby lightning - therefore, there is no such thing as a surge "protector"**. This post focuses on power disturbances; spikes, surges and brownouts.
A surge suppressor, of the grocery-store $5-10 variety is good pretty much only as an extension cord, while providing you a false sense of security. And a surge suppressor connected to your outlet via a 3-to-2 prong adapter (common) is useless. The ground is what provides the protection, and if you defeat the ground you have no protection. Have your electrician upgrade your outlets (cheap) when installing that whole-house surge suppressor.
You need to know surge suppressors have a limited life. Many suppressors, after handling one good spike or surge, can no longer provide suppression. They commonly "fail open", which means they still supply power to the outlets, but the device(s) that provide surge suppression are used up. The better suppressors will have a light to show they are still providing suppression. There is no way to test a suppressor. Replace it with a model that indicates its status. If your suppressor is more than a couple years old, replace it now.
The better surge suppressors ($20 - 50) will provide better suppression, status indicators, reset buttons, line conditioning and possibly ports for phone line and Ethernet pass-through.
If you do run your phone line or Ethernet cable through a surge suppressor, it's possible extra noise will be generated, resulting in poorer dial-up or Internet performance. You'll need to weigh the benefits against the hit on performance. I can tell you I've replaced lots of dial-up modems after lightning storms. Many times we carefully plug the computer and other equipment into suppressors, and forget about the phone line coming into the computer.
Delicate electronics (computers) are susceptible to power fluctuations. When the power dips, a brownout occurs. Although the electronics in your computer can withstand some fluctuation, your data probably cannot. If your computer happens to be copying, backing up data, downloading or calculating at the time a brownout occurs, there will be data corruption. Eventually you'll find the corrupt data and won't know what happened or when. It happened to me during a backup, and I've been struggling to recreate 10 years worth of email for a month.
Appliances in your home or office can cause many power fluctuations throughout the day, including refrigerators, air conditioners, washers and dryers, even microwaves and coffee makers. Line conditioning protects computer equipment from power fluctuations. It's the main reason I use surge suppressors.
An uninterruptible power supply (UPS) contains a battery that will power your system briefly, should the power drop to an unacceptable level. The idea is that you will have time to close everything that's open on the computer and power down safely. The UPS also provides some surge suppression and line conditioning.
How do you pick out a suitable surge suppressor?
- Look for a UL label that states "Transient Voltage Surge Suppressor", or UL 1449.
- Clamping voltage of under 400 V
- Energy absorption of at least 400 joules - 600 or more is better.
- Response time less than one nanosecond
- More details here: http://www.djsociety.org/Surge_1.htm
How do you pick out a suitable UPS?
** Actually, there is something that will protect your equipment from lightning - and surges, spikes and brownouts. Plug everything into surge suppressors, then unplug the suppressor from the wall. Do this when there's a threat of storms, or when you'll be away for a few days, or when the body shop next door fires up it's welder. Seriously, it's that cheap and simple. JUST UNPLUG IT!