Here is a link to information about electric power surges. It is offered to help home dwellers, owners, contractors, insurance agents and all parties interested in reducing the number of cases and severity of equipment damage caused by the unavoidable surges that occur in the electrical systems.
http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf

Here is some general information about what to look for in a surge suppressor. Information taken from Northwest Power Quality Service Center (www.nwpq.com).

What features should I look for in a Surge Suppressor? Expect to pay at least $30 for a good surge protector. A surge suppressor diverts excessive electrical energy away from your equipment to an electrical ground where it is dissipated without doing any harm.

Minimum Specifications:

• UL 1449 Listed - Conforms to Underwriter Labortory's standard UL 1449 for transient voltage surge sppressors (TVSS).
• Peak Surge Current - 39,000 amperes or more. Higher is better. Sometimes called Maximum Transient Current or Maximum Surge.
• UL 1449 Suppressed Voltage Rating - 330 volts gives the best protection. Higher voltage ratings give less protection. Sometimes called Clamping Voltage.
• Energy Rating (Joules) - 420 joules or more. Higher is better.

• Appropriate Connectors and Outlets - An outlet for each piece of equipment. Room for AC adapters (transformers). If you are protecting a TV, VCR, telephone, fax, or com0uter, get a surge suppressor with TV cable connectors and/or phone jacks.
• Indicators - Status or warning lights to indicate that the device is working (not just that it's on). Sound alarm to indicate surges.
• Electrical Noise Protection - For EMI (electromagnetic interference) and RFI (radio-frequency interference).
• Warranty and Insurance - Warranty on surge suppressors of at least 5 years. Warranty on connected equipment of $2,500 - $25,000 or more.

• Cannot protect you from power outages (black-outs) or power sags (brown-outs).
• Cannot protect your equipment from nearby lightning strikes.

• Surge suppressors work only if they are plugged into a properly grounded 3-prong outlet.
• If your house is older and has 2-prong outlets, or improperly grounded 3-prong outlets, have a licensed electrician upgrade your outlets.

• UL STandard 1449 became more strict in August 1998. Older surge supressors may be less safe.
• If you do not see UL-1449 Listed stamped or emossed on your device, it may just be an outlet strip on an extension cord, not a surge supressor.
• Replace an old surge suppressor if it is discolored, overheats, or shows signs of melting.
• If your old surge suppressor has no indicator lights, it may not be working and should probably be replaced.

1. IEEE Guide for Surge Protection of Equipment Connected to AC Power and Communication Circuits
2. Martzloff, F.D. and Lai, J.S., "Cascading Surge Protective Devices: Coordination versus the
   IEC 664 Staircase," Proceedings, PQA'91 Paris, October 1991.
3. Lai, J.S. and Martzloff, F.D., "Cascading Surge Protective Devices: Options for Effective
   Implementations," Proceedings, PQA'92 Atlanta, September 1992.
4. Electrical Power Systems Quality by Dugan, McGranaghan, and Beaty; or the IEEE C62.41 Recommended Practice.