Grounded outlets were not required until the mid 70s. Your home may have been built with two-prong outlets, and a previous well-intentioned homeowner may have replaced the old two-prong outlets with newer three-prong version. However, unless he installed a ground wire, it is still a non-grounded outlet. Outlet testers are an inexpensive way to see if the outlet is wired properly. A tester can be purchased at most hardware and home centers.
If your outlet is not properly grounded or if it is an older two-prong outlet (Figure A) it would be preferable to have an electrician run a ground wire to the outlet.
Electronic equipment must be plugged directly into the surge suppressor with the surge suppressor plugged directly into a grounded wall outlet (Figure B) for full warranty coverage.
Ordinary power strips don’t provide adequate protection. You need a true surge suppressor, which looks very much like a power strip but provides much greater protection. Suppressors can cost from $20 to $150; the best ones can handle high voltage surges and react instantly, an important factor considering that many power surges last just fractions of a second.
To make sure you’re getting the right kind of protection, look for the underwriters Laboratories 1449 rating on a surge suppressor; this is the “gold standard.” Also, make sure your suppressor has an internal fuse to cut the circuit in the event of a longer surge. Buy a suppressor with a good warranty that obligates the manufacturer to reimburse you for the costs of repairing damage or replacing equipment if the suppressor fails. You may also want to consider a suppressor equipped with special features to protect modems, faxes or coaxial cables, since these are common points of entry for power surges. Surge protection devices need a path to ground to work properly. The home must have a grounding point for the surge suppressor to send the overvoltage. The National Electric Code (NEC), article 800 states:
"All power, cable and telephone grounds MUST be bonded to the same grounding electrode system entering a building. This prevents potential ground voltage differences that may be seen across data, power, and telephone lines connected to sensitive electronics."
If you have multiple ground points, these will have to be brought to NEC standards prior to the installation of the surge protection equipment. Improper ground bonding may result in the voiding of applicable warranties.
Three-prong to two-prong adapters must not be used with any surge protection equipment.
More than 50% of today’s residential products contain electronic components and the list is growing. Most people only think of computers, TVs and VCRs when you mention electronic appliances, but many of the newer products, such as stoves, refrigerators and heating and cooling systems contain sophisticated electronic circuits.
Every small surge deteriorates the electronic components in this equipment, which can drastically shorten their designed life. The average home has 2,200 or more surges annually. These surges can be generated from a number of sources, such as heaters, dryers, garage door openers and motors starting on air conditioners, freezers, and well-pumps. Most of these surges are so small the average consumer does not see the damage they cause. However, your electronics take a constant "pounding." When a thunderstorm strikes, the electronic components may fail and you may think lightning caused the damage. In reality the product was already on the brink of failing because of the many constant low-level surges from your own equipment.
Whole-house protection with proper grounding and end-use protection for each piece of equipment will give you the best possible protection available.