A surge protector that doesn't protect

Any device that makes its living standing up to electricity is sure to be dealt a losing hand sooner or later. What then?  What happens to your electronic stuff after your surge protector has dutifully sacrificed itself? As we'll see, there are two possibilities

Of course, this never comes up when purchasing a surge protector.

Just as they divert electricity, industry marketing diverts the attention of the buying public by focusing solely on Joules. Consumers are lead to believe that the more Joules the better, when other features are more important, and the Joules rating is, arguably, not important at all.

Take, for example, the let-through voltage. In simple terms, it is the very definition of a surge, it's the amount of electricity, over normal levels, that a surge protector will allow to pass through to the protected devices. The better the surge protector, the lower the let-through voltage. 

Where Joules does come in handy, is reminding us that surge protectors die. Wikipedia describes the Joules rating as telling us "how much energy the surge protector can absorb before it fails."  

This came up because of a mistake I made.

For years I have been buying surge protectors from APC. For so many years that I forgot why. Thus, when I needed one recently, I purchased a Tripp Lite model.

Not just any one, though, I went for a high end surge protector: an Isobar Ultra.


 It's metal rather than plastic. And, it's relatively expensive, so I opted for one with only four outlets (the Isobar 4 Ultra, shown above).

As far as Joules goes, this baby is loaded wtih 3,300 of them. It has a let-through voltage under 35 (very good) and a response time of zero (also excellent). It has two isolated filter banks, which I take on faith, is better than having just one.

The box it comes in calls it a "Premium Surge Suppressor". Tripp Lite says the "ISOBAR is the world's number one selling premium suppressor series with more than 18 million satisfied customers and a safety-tested history of 20+ years".

It is ISO 9001 certified (again, I'm assuming this is a good thing). At Amazon.com, the four outlet model is rated 5 stars. No one gave it a one or two star rating.

Below is a diagram from the box it came in, further detailing surge protection features that I don't understand.


Perhaps you can see why I made the mistake I did. It seems like a good choice.

But, before throwing out the packaging for my new surge protector, I took a quick look at the included documentation. Techies, after all, read the fine manuals. I didn't expect much, after all, what's there to know about using a surge protector? 

The forgotten reason for buying APC models, that's what. 

See for yourself, here is a PDF of the Owners Manual  for the Tripp Lite Isobar4.


See that box near the top, just above the Installation section (screen shot above). It says

All models feature an internal protection that will disconnect the surge-protective component at the end of its useful life but will maintain power to the load—now unprotected.

Translation: when the thing dies, your stuff is not protected.  

In contrast, consider the APC NET8 surge protector (below) that retails for less than $30.


It is a nothing-special, average, ordinary, middle-of-the-road APC surge protector.

Like other APC models however, it comes with "Catastrophic Event Protection". Here's how APC describes this feature:

SurgeArrest components such as MOVs and Thermal fuse ensure instantaneous reaction to lightning strikes and wiring faults. If the surge components are damaged due to power spike or over voltage, excess power cannot reach your equipment.

The important phrase being "Excess power can not reach your equipment." When the APC NET8 dies, it stops passing electricity through to your devices. If it can't protect your devices, it won't power them at all.

That's Defensive Computing. APC goes on to say

 ... most surge suppressors continue to let power through even after circuits have been damaged, leaving your equipment exposed to other damaging surges.

The Tripp Lite Isobar "premium" models will, indeed, provide unprotected power after they have failed.

That's just not right.

Update: Feb. 10, 2012. For more on this, see After a surge protector fails.

Copyright © 2012 IDG Communications, Inc.

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