How Smart Power Strips Work


A smart power strip can help keep electronic accessories from wasting power. This one is a Smart Strip from BITS Limited.  See more green science pictures.
Photo courtesy Bits Limited

Turn off the lights in your computer or TV room, and you'll probably see eyes peering through the darkness. All of those glowing LEDs, clocks and power switches are sneaky electronic vampires. While you can't slay them with a stake through the heart, you might be able to manage these vampires more easily with the help of a smart power strip.

Traditional power strips are an affordable way to expand the number of electrical outlets in your home. But their convenience can encourage you to leave electronics plugged in all the time -- and many devices keep drawing power even when you're not using them. Printers, DVD players, computers and plasma TVs are all examples of products with standby modes that make them convenient to use but suck significant power on the sly. This so-called phantom power drain costs you money, wastes electricity and ups your carbon output to boot.

Smart power strips, on the other hand, work to reduce your power usage by shutting down power to products that go into standby mode. Doing so may save you some serious cash. Statistics vary, but experts say standby power consumption in an average home ranges from 5 percent to 10 percent of your household energy consumption. It can also account for about 1 percent of worldwide carbon dioxide emissions [source: Lawrence Berkley Nation Laboratory].

You could combat vampire power by continually unplugging your gadgets, but with a smart power strip you won't have to. Keep reading to see which products suit your needs and how they work to make your home electronics more energy efficient.

Smart Power Strip Basics

The Watt Stopper IDP-3050 comes with a motion sensor.
The Watt Stopper IDP-3050 comes with a motion sensor.
Photo courtesy Watt Stopper/Legrand

Smart power strips come with a range of bells and whistles, but they all have two basic components: electrical outlets and circuitry that monitors and controls those outlets. For example, when a printer plugged into a basic smart strip goes into standby mode, its power consumption drops. The circuitry detects the change and cuts the power to that outlet. The rest of the outlets in use stay on. Many smart power strips also have one or two unmonitored, always-on outlets. These are the ones you'd use to plug in the devices that always need power, like your cordless phone base or alarm system.

Monitoring several outlets and cutting the power to each one separately can lower your total electricity use, but in some situations it's not the most efficient way to get the job done. Think of the devices that you can really only use when the TV is on -- like a DVD player, a PlayStation 3, speakers and an A/V receiver. Some power strips let you group such items together, turning all of them on or off at the same time.

One such strip is the Smart Strip LGC3 from Bits Limited, which comes with 10 color-coded (blue, red and white) outlets. The blue outlet is the control outlet, and all the white outlets are connected to it. If you plug your television into the blue outlet and all those other accessories into the white ones, the Smart Strip will control the accessories based on what the TV is doing. The red outlets are always on, so you could use them for a TiVo or other device that might need power even when the TV is off.

The Smart Strip does all this by monitoring just the control outlet. When power shifts 10 percent above the preset threshold on the control outlet, a sensor circuit detects that you've turned on the TV, and it triggers power to the outlets controlling your TV-related accessories. When power to the control outlet drops, the Smart Strip cuts power instead.

Next, we'll look at some other features that can make smart power strips more useful or more convenient.

Popular Smart Power Strips

Belkin's Conserve power strip has a remote control.
Belkin's Conserve power strip has a remote control.
Photo courtesy Belkin

Today's smart power strips can do more than just turn outlets on or off. The Isolé IDP-3050 is one such strip. It's a power strip with surge protector features, with one nifty upgrade: It has a motion detector, too. When there's a person nearby, all outlets are active. When the room is unoccupied for a set length of time -- anywhere from 30 seconds to 30 minutes -- the IDP-3050 stops power to six of its eight outlets. The amount of time a room needs to be empty before the power goes out is up to you.

The motion detector uses a passive infrared system. Sensors detect the infrared energy, or heat, all humans radiate. If you remove that infrared energy by leaving the room, the motion sensor, which has a maximum range of about 300 feet (91 meters), sends the signal to start the countdown to power shutoff. If you walk back into the room, the sensors detect your heat and stop the countdown.

Like the Isolé, Belkin's Conserve surge protector has eight outlets, two of which provide constant power. You control the other six outlets with a remote control, which is designed to look like a light switch and slides in and out of a mount on your wall. This is a major benefit for people who have outlets in hard-to-reach places -- you don't have to flip multiple switches or cram your arm into a tight space behind your entertainment center to shut off the strip. The remotes communicate using radio waves, which means they can work through walls. And since each remote can work on several frequencies, you can decide whether to control multiple Conserve strips with a single remote or with a different one for each strip.

Some smart power strips also come in much smaller packages than the Conserve or the Isolé. The Mini Power Minder is one example. It's a two-outlet smart strip designed for smaller spaces. It also uses a USB cable to help monitor your computer usage. You connect one end of a USB cable to the Minder and the other to your computer. When you shut down your computer for the day, the Minder senses the change in power levels and cuts electrical current to the secondary outlet.

All of these smart strips have some limitations that make them most suitable for specific electronics setups. Keep reading to see how you can integrate power-saving devices into your home and combat challenges inherent to using them.

Using Smart Power Strips Properly At Home

When you use them correctly, smart power strips can help you conserve energy in your home. But you'll want to think through your electronics setup so you can choose the best strip for your needs. There are lots of potential challenges, but we'll highlight some common issues here.

If you choose a power strip that uses a USB cable to detect power levels from your computer, keep in mind that many computers power their USB ports all the time. If your computer is one of these, a smart power strip plugged into the USB port would never shut anything down. However, some computers let you configure whether USB ports are powered when the computer is shut down, so with a bit of tweaking, this kind of strip could work just fine.

Smart power strips that plug into the wall can have power detection challenges, too. If the strip's sensors aren't precise enough to detect when devices go into standby mode, electronics can continue to draw power when they don't need to. Some power strip models have controls that let you adjust the voltage sensitivity. If you notice that devices are still in standby when they should be shut down, try adjusting this setting.

Motion detector smart strips may pose problems when used with some types of devices. If you plug a computer into one of these strips and walk out of the room without saving your data, you might come back to find that everything has shut down with your work unsaved. For this reason, motion detector strips are best used with lights and other devices that won't be negatively affected by sudden shutdowns.

Of course, some products, such as a DVR, need ready access to power so they can perform scheduled tasks. An abrupt power loss can also damage some devices, such as inkjet and laser printers that have a controlled shutdown sequence. The best way to turn off these products is to use their onboard power switches rather than a smart strip.

Finally, you don't have to switch to smart strips to fight vampire power. Instead, you can just remember to unplug devices or flip the master switch on your regular power strips. Most computer operating systems also have settings that will let you run your computer in a more energy-efficient mode. No matter which combination of methods you choose to save energy, in the end, you may very well see nice savings on your electrical bill and reduce strain on the environment, too.

Related HowStuffWorks Articles

Sources

  • Belkin Conserve Product Page. (July 8, 2009)http://www.belkin.com/conservenow/
  • Bits Limited Smart Strip Product Page. (July 8, 2009)http://bitsltd.net/images/stories/file/Smart-Strip-Full.pdf
  • Gizmodo. "This Just In: Power Strip Smarter Than Tara Reid." Jan. 11, 2006. (July 8, 2009)http://gizmodo.com/147929/this-just-in-power-strip-smarter-than-tara-reid
  • The Economist. "Pulling The Plug On Standby Power." (July 8, 2009)http://globaltechforum.eiu.com/index.asp?layout=rich_story&channelid=3&categoryid=10&title=Pulling+the+plug+on+standby+power&doc_id=8293
  • Hudson, Travis. "Smart Power Strip Auto Shuts Down Peripherals." Gizmodo. May 18, 2007. (July 8, 2009)http://gizmodo.com/261735/smart-power-strip-auto-shuts-down-peripherals
  • LaMonica, Martin. "Bits Smart Surge Strip." CNET. June 15, 2009. (July 8, 2009)http://www.cnet.com/2300-19745_1-10001041-2.html
  • Nadel, Brian. "12 Money-Saving, Power-Sipping Green Gadgets for Earth Day." PC World. April 21, 2009. (July 8, 2009)http://www.pcworld.com/article/1628963/12_moneysaving_powersipping_green_gadgets_for_earth_day.html
  • Raphael, JR. "Unplug For Dollars: Stop 'Vampire Power' Waste." PC World. Nov. 9, 2008. (July 8, 2009)http://www.pcworld.com/article/153245/unplug_for_dollars_stop_vampire_power_waste.html
  • U.S. Department of Energy. "Your Home's Energy Use." (July 8, 2009)http://www1.eere.energy.gov/consumer/tips/home_energy.html
  • Watt Stopper/Legrand Product Page. (July 8, 2009)http://www.wattstopper.com/getdoc/1105/C-119%20IsoleCut_112008.pdf
  • Wilson, Mark. "Mini Power Minder: A Plug That Cares." Gizmodo. Nov. 19, 2006. (July 8, 2009)http://gizmodo.com/gadgets/gadgets/mini-power-minder-a-plug-that-cares-215879.php