Phantom load: Difference between revisions
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'''Phantom load''', sometimes referred to as standby power or leaking [[electricity]] is the power consumed by any device while it is switched off. |
'''Phantom load''', sometimes referred to as standby power or leaking [[electricity]] is the power consumed by any device while it is switched off. The earliest known use of the term was in the June/July 1989 issue of Home Power magazine [http://homepower.com]. |
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Many domestic [[appliance]]s consume power when they are nominally off. Stereos, [[VCR]]s and [[television set]]s are examples. The phantom load can be caused by miniature [[transformer]]s (such as [[wall wart]]s) that convert AC electricity into DC electricity. The conversion is most efficient with large power draws, such as [[refrigerator]]s, and least efficient with device that require little power, such as digital [[clock]]s. Phantom load is also caused by devices which feature small [[LED]]s or other indicators that they still have power; these indicators obviously use power themselves. |
Many domestic [[appliance]]s consume power when they are nominally off. Stereos, [[VCR]]s and [[television set]]s are examples. The phantom load can be caused by miniature [[transformer]]s (such as [[wall wart]]s) that convert AC electricity into DC electricity. The conversion is most efficient with large power draws, such as [[refrigerator]]s, and least efficient with device that require little power, such as digital [[clock]]s. Phantom load is also caused by devices which feature small [[LED]]s or other indicators that they still have power; these indicators obviously use power themselves. |
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Finding phantom loads is not always easy. "Gas" stoves that use an electric clock constitute a phantom load. Recommended methods for finding phantom loads include turning off all lights at night and looking for any LEDs or other glows in the house. Any device that requires resetting after a blackout or power surge is a cause of phantom load. "Instant on" features are often an indicator of phantom load. |
Finding phantom loads is not always easy. "Gas" stoves that use an electric clock constitute a phantom load. Recommended methods for finding phantom loads include turning off all lights at night and looking for any LEDs or other glows in the house. Any device that requires resetting after a blackout or power surge is a cause of phantom load. "Instant on" features are often an indicator of phantom load. |
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A simple test using a 'true power meter' or energy meter found that an all-in-one hi-fi unit (CD, tuner, tape deck) consumed 20W when 'off' and 60W when on but silent. Similarly, a recent microwave oven with a clock used 15W when not cooking (A similar model with a mechanical timer used no measurable power when not in use). It was found that recent models generally used more power in standby than devices from 5 years ago!{{Fact|date=February 2007}} A well designed study done by the American magazine Home Power found the average American household supports 1.45 kilowatt hours of phantom loads per day.[http://www.christian-ecology.org.uk/m0402.htm] |
A simple test using a 'true power meter' or energy meter found that an all-in-one hi-fi unit (CD, tuner, tape deck) consumed 20W when 'off' and 60W when on but silent. Similarly, a recent microwave oven with a clock used 15W when not cooking (A similar model with a mechanical timer used no measurable power when not in use). It was found that recent models generally used more power in standby than devices from 5 years ago!{{Fact|date=February 2007}} A well designed study done by the American magazine Home Power magazine [http://homepower.com] found the average American household supports 1.45 kilowatt hours of phantom loads per day.[http://www.christian-ecology.org.uk/m0402.htm] |
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Although not considered a true phantom load, [[desktop computer]]s left on will draw around 150W continuously. A [[laptop]] generally uses less than 50W, usually around 20W average.{{Fact|date=February 2007}} |
Although not considered a true phantom load, [[desktop computer]]s left on will draw around 150W continuously. A [[laptop]] generally uses less than 50W, usually around 20W average.{{Fact|date=February 2007}} |
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Revision as of 22:55, 5 November 2007
Phantom load, sometimes referred to as standby power or leaking electricity is the power consumed by any device while it is switched off. The earliest known use of the term was in the June/July 1989 issue of Home Power magazine [1].
Many domestic appliances consume power when they are nominally off. Stereos, VCRs and television sets are examples. The phantom load can be caused by miniature transformers (such as wall warts) that convert AC electricity into DC electricity. The conversion is most efficient with large power draws, such as refrigerators, and least efficient with device that require little power, such as digital clocks. Phantom load is also caused by devices which feature small LEDs or other indicators that they still have power; these indicators obviously use power themselves.
For any single appliance the load is never very large (the most inefficient designs draw 15-20 watts [2]), however when factored over all of the appliances in a country like the U.S. the load can come to billions of watts. Some studies have suggested that the total phantom load caused by the United States alone would provide enough power to handle the electric needs of Vietnam, Peru, and Greece [3]. Suggestions for reducing the phantom load include the use of a surge protector or a power strip. When the supply is turned off, the appliance can no longer draw power from an outlet, thereby eliminating phantom load.
Chasing phantoms
Finding phantom loads is not always easy. "Gas" stoves that use an electric clock constitute a phantom load. Recommended methods for finding phantom loads include turning off all lights at night and looking for any LEDs or other glows in the house. Any device that requires resetting after a blackout or power surge is a cause of phantom load. "Instant on" features are often an indicator of phantom load.
A simple test using a 'true power meter' or energy meter found that an all-in-one hi-fi unit (CD, tuner, tape deck) consumed 20W when 'off' and 60W when on but silent. Similarly, a recent microwave oven with a clock used 15W when not cooking (A similar model with a mechanical timer used no measurable power when not in use). It was found that recent models generally used more power in standby than devices from 5 years ago![citation needed] A well designed study done by the American magazine Home Power magazine [4] found the average American household supports 1.45 kilowatt hours of phantom loads per day.[5]
Although not considered a true phantom load, desktop computers left on will draw around 150W continuously. A laptop generally uses less than 50W, usually around 20W average.[citation needed]
From the US department of Energy:
"Many appliances continue to draw a small amount of power when they are switched off. These "phantom" loads occur in most appliances that use electricity, such as VCRs, televisions, stereos, computers, and kitchen appliances. In the average home, 75% of the electricity used to power home electronics is consumed while the products are turned off. This can be avoided by unplugging the appliance or using a power strip and using the switch on the power strip to cut all power to the appliance."[6]