Avoid This Mistake When Buying a Surge Protector

Last Updated: Oct 09, 2020

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Most electronic devices are very sensitive to electrical power surges and can get easily damaged if one occurs. So it’s a smart idea to invest in a good surge protector. But if you make the same mistake I made, you may still end up with damaged equipment.

We have had a lot of thunderstorms and rain over the past couple of weeks in Georgia. But I wasn’t worried, because most of the electronic devices in our household are either connected to an Uninterruptible Power Supply (UPS) or a surge protector. I have two APC Back UPS Pro 1500* units in my home office and one in the family room. This ensures, that all infrastructure to support my job remain working in case of a power loss.

Uninterruptible Power Supply vs Surge Protector

A UPS device also doubles as a surge protector and on most you will find outlets marked as “Battery” and “Surge Protection only”. The latter don’t provider any battery backup, as the name implies, but the former include surge protection as well.

APC Smart UPS 1500 and surge protector
Good investment: APC Smart UPS 1500

During a recent, heavy thunderstorm, the lights in our house flickered for a split-second and I could hear the UPS in my office beep for a moment. “I’m glad I have a UPS”, I thought. To double-check that everything was in order, I walked into my office and noticed my iMac complaining that an external disk was not properly unmounted. That was a sign of power loss of one of the external drives. Plus, I noticed that internet wasn’t working.

Damage Despite UPS

Upon further investigation, I concluded that the following devices suffered damaged and were non-operational.

Both devices were connected to the same UPS, which had 5 other devices connected as well that remained unharmed. What puzzled me even more was that the UPS itself seemed unharmed too. I called APC and asked the following, simple questions:

  1. Under what circumstances can a power surge damage 2 out of 5 connected devices, without damaging the UPS itself?
  2. What can I do to prevent that in the future?

As it so happened, I reached the most incompetent engineer I had ever spoken to. He couldn’t even form a coherent sentence and the takeaway from that call was: He cannot predict thunderstorms and APC covers such losses. The latter sounds good, but in reality you may only get the time-value of damaged devices. For electronics, that’s usually nothing the day after you bought them.

What About Your Data Lines?

I called APC again the next day and was connected to the very same, incompetent support engineer. Then I tried their chat function and talked to a pre-sales guy. After describing my issue, he mentioned the magic words “data line”. Of course, how could I have not thought about that! Surges don’t necessarily have to travel through power lines, they can enter your home through other data lines, such as your cable feed.

APC Back UPS 1500 and surge protector
I should have used those coax connectors

Comcast is my internet service provider (ISP) and their cable enters the house at my home office. From there it goes straight into my cable modem – unprotected!

I used to run this coax cable through the UPS, but changed that a couple of years ago when I had noise on the line and suspected the UPS to be the cause of it – mistake! It was obvious how a surge on the coax line could affect the AirPort Extreme, which was connected directly to the cable modem. But, how could that affect my external hard drive? To understand that, you need to know how those devices are connected with each other:

Comcast —> {coax} —> cable modem —> {ethernet} —> AirPort Extreme —> {ethernet} —> Thunderbolt to Ethernet Adapter —> {Thunderbolt} —> LaCie d2 —> {Thunderbolt} —> LaCie 5big Thunderbolt 2 Raid —> {Thunderbolt} —> iMac

So the surge must have come in via the coax line, went through the cable modem and into the AirPort Extreme, out the ethernet line, through the Thunderbolt to Ethernet Adapter and into the LaCie d2. Interestingly enough, the cable modem wasn’t damaged but everything else was. Fortunately, the mess stopped at the LaCie d2 instead of continuing to the LaCie 5big and the iMac. If I had lost those too, it would have been a huge damage.

The good news is, the LaCie d2 was only a clone of the LaCie 5big, so no critical data was impacted.

Lesson Learned

One of the first things I did after this event was to connect the coax cable to the UPS and go from there to the cable modem. I also double checked that CrashPlan was working properly, to make sure I wouldn’t suffer complete data loss in case of a fire or other catastrophic event that would destroy all office equipment. To learn more about my backup strategy, see this post.

It’s also important to note that no consumer-grade surge protector will help if your house suffers a direct lightning strike. That’s just too much energy to absorb, so be aware and keep an offsite backup.

3 thoughts on “Avoid This Mistake When Buying a Surge Protector”

  1. Hi Michael,
    I agree with your assessment. However, the original problem of noise on the data line still exists if you go back to routing through the UPS. This issue is well documented online and in Comcast’s own website. I believe Comcast has gone as far as removing data line protection from customer’s homes, as the noise can impact not only your line but your neighbors as well.

    I would be interesting to learn if you find a solution that provides coax surge protection without the noise, as I haven’t been able locate such a device yet. Thoughts?

  2. Ah, yes. There is a problem living in the Thunderstorm Belt. When I lived in Seattle, the rain often seemed unending but thunder was rare. Now that I’m back in Auburn, Alabama not far from you, I hear thunder even when it’s not raining. I love thunder, but I worry about its effects.

    Like you, I had a thunderstorm that took out my cable modem. Since nothing else was affected I suspect the lightning came in on the cable rather than the powerline. Since the one I replaced it with cost almost nothing at a thrift store, I’m not worried about it. But if I get one of those fancy $150 ones, I’ll looking into lightning protection on the cable.

    Those who have electronics scattered throughout their house might want to look into whole house surge protection. It’s installed where the power comes into your house, typically at the breaker box, and offers far more robust protection that the little outlet devices. Here are some descriptions:



    Keep in mind that a lot of modern appliances, such as refrigerators and stoves, have electronics that’s just as susceptible to lightning as a computer. And replacement parts can be very expensive, since there’s no competition.


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