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Practical Computer Advice
from Martin Kadansky
Volume 14 Issue 4
April 2020
Smart Surge Protectors: A Mostly-Dumb Idea


"Smart" or "green" surge protectors have been available for many years now, and many energy-audit companies and electric utilities also give them away for free, touting their ability to save you money by reducing your power consumption. In my experience these well-intended devices rarely ever work out that way.

The typical smart surge protector

"Smart" or "green" surge protectors typically have 3 types of power outlets:
  • 1 Master outlet: This is where you plug in your computer.
  • 3-4 "Slave" or "Green" outlets: You plug any dependent separately-powered devices into these, i.e., any devices which you would only use while your computer is powered on, including an external monitor, USB hub (*), powered external backup drive, computer speakers, USB-connected non-shared printer, scanner, etc.
  • 3-4 Always-powered outlets: You would plug any independent powered devices into these, those that you would need to have powered on even when your computer is off or sleeping, including your internet modem, wireless router, shared wireless printer, desk lamp, desk phone, smartphone or tablet charger, fan, etc. If you have a larger number of independent devices than always-powered outlets, you can certainly plug the rest into a separate, regular surge protector.
Some smart surge protectors also have a "sensitivity" switch to adjust the Master outlet's ability to detect that your computer is drawing power. Some even come with mobile apps that let you configure many additional features.

(*) Devices which get their power solely from a USB cable (like most portable external drives, DVD players, mobile device chargers, cordless mouse and keyboard receivers, etc.) would plug into a USB port to get their power (and data), either into a port directly on the computer, or one that's on a USB hub. If you then plug your hub's power cable into a "slave" outlet on a smart surge suppressor, make sure that you only connect dependent USB devices to that hub. Otherwise, when you turn off your computer and that in turn powers off your hub, if you have plugged (for example) your iPhone, iPad, or Android charger into your hub, your mobile device's battery will not get charged while your computer is off, which is probably not what you want. Your hub powering off can also cause problems with an external USB hard drive. So, if you have multiple dependent and independent USB devices, depending on how many built-in USB ports your computer has, you might need to get a second USB hub to keep your independent USB devices separate, and then make sure that that second hub always has power.

The way a smart surge protector is intended to work

Once you have sorted out which devices' power cords should be plugged into which outlets (and which USB devices should be plugged into which USB hub), here's what's supposed to happen:

  • When you computer is on, your smart surge protector detects that it's drawing power, and then powers all of the "slave" outlets, supplying power to all of your dependent devices.
  • When you turn your computer off (or put it into sleep or hibernate mode), your smart surge protector detects that, and then turns off the power to all of the "slave" outlets, powering off all of your dependent devices.
  • Regardless of whether your computer is on or not, your smart surge protector supplies power to all of your independent devices.
This generally works great if:
  • You understand all of this, and plug each of your devices into the appropriate outlets.
  • You have enough "slave" outlets to cover some (if not all) of your dependent powered devices.
  • Your computer is always plugged in to the Master outlet, and always draws enough power for your smart surge protector to tell that it's on, so it can in turn power on (or off) all of the "slave" outlets. This is likely to work best for a desktop computer.
  • You remember all of this for the future when you get new equipment, or when a given device might change from being dependent to being independent, or vice versa.
If you get this to work, I recommend labeling everything, or writing up a summary and taping it to the surge protector, or somewhere nearby.

What might go wrong in the short term

A smart surge protector will probably work better with a desktop computer, assuming it can correctly detect when the computer is powered on or off.

However, if you have a laptop computer, trying to get a smart surge protector to work may be extremely frustrating because it might not be able to tell when your laptop is on, especially when:
  • Your laptop is on, plugged in and fully charged, so it might not need to draw any power.
  • Your laptop is on, plugged and almost fully charged, so it might be drawing only a tiny amount of power as it approaches being fully charged.
  • Your laptop is on and nearby, but not plugged in to your smart surge protector at all, running on battery power instead.
So, in the worst case your laptop could be continuously on but (depending on what you're doing) changing between the above 3 states, which will probably cause your smart surge protector to turn its "slave" outlets on or off at apparently random moments.

What might go wrong in the long term

At some point in the future, you may choose to:
  • Replace your computer.
  • Change from a directly-connected USB printer to a wireless one.
  • Get one or more new mobile devices.
  • Replace your backup drive, or buy a second one.
  • Acquire or replace some of your USB devices, for example a keyboard, mouse, headset, digital camera, recorder, USB wireless adapter, etc., or get a new USB hub.
If you don't remember how you set up your smart surge protector, you may plug a power or USB cable into the wrong outlet or port, and end up having confusing problems.

For all of these reasons, for most people a smart surge protector is likely to be a frustrating and confusing waste of time, with minimal energy- and cost-saving benefit.

Where to go from here
  • google: smart surge protector
  • Unless you're very technically-minded, I also suggest that you stay away from smart surge protectors that require you to download and use an app (software) to configure them.
  • If you do choose to use a smart surge protector, I recommend that you replace it every 3-5 years, since (like any other surge protector) its ability to protect your equipment from surges is likely to fade away over time.
How to contact me:
email: martin@kadansky.com
phone: (617) 484-6657
web: http://www.kadansky.com

On a regular basis I write about real issues faced by typical computer users. To subscribe to this newsletter, please send an email to martin@kadansky.com and I'll add you to the list, or visit http://www.kadansky.com/newsletter

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I love helping people learn how to use their computers better! Like a "computer driving instructor," I work 1-on-1 with small business owners and individuals to help them find a more productive and successful relationship with their computers and other high-tech gadgets.

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