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.