Is it on, off, or idling and how to tell

February 17, 2010
I’m sure most of you have heard or read that some appliances still use electricity when they’re “off.” There is no doubt this is true, but how can you tell? Identifying what’s idling and what isn’t (without paying money for something like a Kill A Watt Monitor) is a good first step.

How much energy is really being wasted?

Measuring the ethernet router’s power supply An idling appliance is something that uses electricity when it’s “off.” When “off,” they could use anywhere from about 5 to 25 watts. Usually these appliances have internal clocks or settings. Unplug the appliance if you don’t care to keep time or settings you may have saved.

A disconnected cell phone charger, laptop power supply, or any external power supply not connected doesn’t need to be plugged in. Depending on how they work, they could use anywhere from 0 to 10 or more watts.

Here are the results (in watts) of some measurements I took:
  • Nokia cell phone charger (not connected):
  • Laptop power supply (not connected):
  • Ethernet router power supply (not connected):
  • Cassette deck, “standby” (it’s not labeled “off”):
  • VCR/DVD player, no clock, completely “off”:
  • Older PlayStation 2 turned “off” from the front button:
  • Older PlayStation 2 turned off from the back switch:
  • Computer, completely “off”:
  • Older VCR with clock, completely “off”:
  • A Sony stereo system with disc changer, cassette deck, and clock, completely “off”:

How can I tell if something is idling?

Common Indicators:

  • Lights or a display is still on and working
  • It hums or makes any noise when you put your ear right up to it
  • It can automatically turn itself on (as through a timing function) if it’s “off”
  • It is warm to the touch due to power dissipation

Typical Appliances that Idle when “Off”:

  • Desktop computers made after 1995 (or after ATX was introduced)
  • Laptops
  • Computer monitors and TVs
  • VCR/DVD/Blu-ray players
  • PlayStation, Xbox, Nintendo, and other gaming systems
  • Satellite receivers
  • Cell phone chargers
  • Answering machines
  • Anything that has an external power supply
  • Anything that keeps time

Push-Button Switches

Another way to tell if an appliance is idling is by the power button or switch. If the power button is small and requires a gentle push with a subtle “click” or “tap” sound, it likely idles.

If the power button feels heavy duty, making a “click-cling” or a “click-clack” sound, it probably doesn’t idle. This is because these switches usually switch the wires straight from the power cord. It’s the equivalent to unplugging it. This is common in much older appliances, especially stereos and amplifiers.

Toggle Switches

If you have an appliance that has a toggle or flip switch like a power strip, it probably doesn’t idle. However, if the switch is small, thin, or light, it might use idle power.

Too Much Hype?

Another point I want to get across is don’t be too optimistic. Most idling appliances use very little electricity. Also, new power supply designs continue to increase in efficiency during idle time. Consider that a laptop or cell phone also uses idle electricity when it’s completely “off” (unless you have no battery).

Air conditioners and heaters make the meat of your electric bill, not idle power or lighting. Unplugging any one appliance will probably make a negligible difference. It’s when you have several that they have an impact.

Turning off a power strip to everything you’re not using is a good idea. Even the Smart Strip uses some idle power. If you’re still using any incandescent light bulbs, you’ve got a slightly bigger problem than idle power.