Power quality at home

Did you know that your expensive electronic equipment could be damaged because of a power fluctuation due to a lightning strike or a power quality problem? This can happen when changes in the power entering your electrical equipment or appliances interfere with the normal operation of that equipment.

Power quality problems can mean resetting all of your digital clocks, losing anything you hadn't saved on your computer or damage to your electronic equipment like entertainment systems.

What causes power disturbances?

A number of factors can cause power disturbances, including lightning strikes, a short-circuit in your home wiring or power system outages. Poor grounding and improper wiring also can contribute to home power quality problems. These disturbances can cause voltage surges and spikes that can be harmful to your sensitive electrical equipment/appliances.

Although recently gaining in popularity, a tankless water heater can cause fluctuations that can damage other electrical appliances. Read more about this on the tankless water heaters page.

Simple solutions

To keep power disturbances from affecting your household electronics, preventive measures are your first line of defense. Following are some steps you can take and guidelines to follow at home. An electrician may be required in some cases.

  • Correct wiring and grounding problems: Proper wiring and grounding of your entire home is essential for electronic equipment to operate smoothly. The traditional "safety ground" protects people, but must be effectively connected and properly wired to provide the performance needed by sensitive electronic equipment. Problems may be difficult to diagnose because symptoms are non-existent unless equipment fails.

    Inexpensive outlet tests are available at electrical supply stores to safely and economically test an outlet. To take care of any wiring or grounding problems you'd rather not do yourself, call an electrician.
  • Move offending equipment: Even one appliance on the same circuit with your electronic equipment can produce spikes and surges. Appliances most likely to cause problems include shavers, hair dryers, electric tools, burglar alarms, cordless phones and heaters. Moving offending equipment to a different circuit can sometimes do the trick.
  • Separate circuits: If you are building a new home or remodeling, consider setting aside circuits specifically designed for your most sensitive equipment that will isolate it from offending appliances.
  • Use surge protection devices: Surge protection devices (SPDs) are the simplest, least expensive "power conditioning" devices. They reduce the size of voltage spikes to a safe level for your sensitive electronic equipment. The equipment plugs into the surge protection device, which plugs into the wall socket.

Back to top

Choosing a surge protection device

Purchase an SPD that will protect all electrical entrances to the sensitive equipment. Dual protection such as this is called "surge reference equalizer." This means computers, fax and answering machines should be protected on both the power and telephone lines; televisions and related media accessories on both power and cable lines. This is because it does no good to protect the power to sensitive equipment, only to have the surge enter through the phone or cable lines.

  • Check for UL listing: The surge protection device should have a UL 1449 3rd Edition listing for electric and cable television lines. A surge protection device that protects both electric circuits and telephone lines will be listed with both UL 1449 3rd Edition and UL 497a, respectively.

    The listings will be verified on the back of the device by a UL sticker. Make sure your surge protection device has "UL Listed" on it, not just "UL Approved" or "UL Tested." You should also choose a device with an indicator light or other diagnostic feature to confirm the device is working.
  • Clamping voltage: Clamping voltage is the typical peak voltage allowed by the device under test specifications. The package should have a UL 1449 3rd Edition listing, generally between 330 and 600 volts. For 120-volt circuits, 330 volts provides the most protection. Voltages higher than the range (330 to 600 volts) should be avoided to protect 120-volt circuits.
  • Protection modes: At a minimum, the device should provide protection from line (or hot) to ground, and line to neutral. More desirable models have a third mode called neutral to ground.
  • Warranties and insurance: While most manufacturers warrant their products, many also offer insurance for your equipment in case of damage as a result of surge suppressor failure. Terms vary and should be considered carefully to determine if such coverage is of value to you.

Using a surge protection device

  • Ensure that all electrical entrances to the equipment are protected by an SPD with the surge reference equalizer capability.
  • Plug the SPD into an outlet that is properly wired and grounded, and make sure that your meter and circuit breaker box are properly grounded.
  • Check the indicator light or other diagnostic feature on the SPD regularly to ensure it is working.
  • Never plug an SPD into an extension cord.
  • Do not plug one SPD into another.
  • Do not use an SPD that smells hot or burned.
  • Do not plug an SPD into an outlet protected by a ground fault circuit interrupter (GFCI).
Powerband