Secrets of Surge Protection!

(Or:  How To Increase The Life Of Your Electronics)
December 2013

ou're probably familiar with those so-called "surge protector" power strips that are just about everywhere.   The basic idea is that they're supposed to divert harmful surges so they don't damage your equipment.

These common types of surge protectors (even the $50 ones) are all built around a 25-cent part.  And unfortunately for you and me, that 25-cent part gives very little real protection.  In fact, it promotes a false sense of security that can be worse than useless.  It could even cause a fire when you're not home.

Here's how conventional surge protectors work.  The "active ingredient" is a thing called a metal oxide varistor (MOV), which is supposed to divert surge current onto the ground wire.   If everything worked the way it should, that surge current would go harmlessly out of your building and into the ground. 

Very often, that's not what actually happens.

First of all, high voltage doesn't always go where we think it will.  What seems like a good path to ground for, say, 120 volts AC might not be a good path for a surge.  High voltage surges (or "transients") might decide to take a detour through your favorite appliance, your computer, or your cable modem.  On the way, these devices get fried.  Just for example, high voltage surges can easily find it unappealing to pass through little things like bends or kinks in the wiring.  These can cause impedances that don't affect your 60 Hertz AC current.  When the time comes and a surge is seeking a path to ground, it chooses another route down through your house wiring, and it could ruin more than your day.

There's another really major drawback to metal-oxide varistors.  They fail, easily.  You won't know if or when that failure has happened.  Because it acts as a shunt to the ground, rather than being in the regular path (series) of the circuit, you won't have any indication whether it's still good or not.  Your appliances will still work.  The outlets on the "surge protector" will still work.  The MOV could be toast, but you'll go along thinking you're alright.  This is really just not a good situation to be in.

"But," someone says, "we don't get many lightning strikes here".   Doesn't matter.  You can get surges from refrigerators, air conditioners, even from downed trees hitting the lines a few miles away.  In fact, surges can happen on a clear day, literally "out of the blue", for no apparent reason (seen it happen).  And worse, you won't always know it.  So, that $50 "home theater power center" could be quietly failing to protect you already.   At the same time, it's polluting your building's ground wire with voltages that should not be there.  A lot of electronic equipment (if not all of it!) uses the ground wire as a zero-volt reference, and when you start messing with that, you get erratic behavior (at best).  Cheap "surge protectors" can play havoc with equipment, creating ground loops, noise, malfunctions... basically a bunch of "gremlins".   (I have a special story about how an old power strip messed with our refrigerator and almost burned up the motor, but I'll save that for another article.)

The Problem, Solved!

An engineer friend of mine used to say "The best inventions are from the first chapter of the physics book".   Well, not really the first chapter, but the beginning of each chapter. What he meant was that good inventions rely on simplicity and basic principles. 

Here's a basic principle for you:  the principle of reactance.  Picture this.  If you put your hand gently into the water, you can go right down through the water with no problem.  Now, if you hit the water hard, it isn't so easy.  They say if you hit the water fast enough, it's like hitting pavement.  That's a great way to think of reactance.   The faster a surge tries to rise, the more resistance it encounters.

Today there is a type of surge protector based on this principle.  It provides that reactance I was talking about.  Not with water (obviously), but with a massive inductance.  It acts transparent to your ordinary house current, but as soon as it gets hit with a surge, it acts like a stone wall.   This is called "series mode" surge protection.  It is directly in line with the circuit, rather than being a shunt to ground.  And it's good.

When I first learned about this technology, I couldn't race fast enough to get it.  I'd seen enough fried electronics to know that conventional units were not working so well.  And when I switched over, I was definitely not disappointed.  If you're already wondering where you can get your hot little hands on one of these gems, they're made by SurgeX and you can get them here.   (I also have a few more links at the bottom of this page.) 

Still going strong, nearly a decade later!

I can't even begin to describe how great these things are.  The inductor is completely unaffected by surge voltage.  Unlike with MOV-based units, you don't have to replace the unit every time there's a surge.  A SurgeX lasts indefinitely.  They use their products in Carnegie Hall, Yankee Stadium, and other places that take their equipment seriously.  There's no cheesy little 25-cent part to fail. 

Speaking of 25-cent parts, another danger of MOV-based "surge protectors" is that even when they do work as designed, they can easily fry other stuff in your building.  Remember I said that MOV's only redirect the surge!   So, that power strip where you plug in your microwave could be slowly destroying your computer, your stereo, your TV... and you won't even know it, until the day they quit "mysteriously".  I have a feeling that a lot of hard drive failures and data losses are due to this fact, also.  

In all likelihood, a lot of "wall wart" power supplies fail because of small surges that otherwise go undetected.  As you probably know, those "wall-warts" are responsible for a lot of fires.   Getting a SurgeX can give you an extra line of protection in those cases where it's not practical to unplug the wall warts when you're not home.   Considering these protectors can stop a surge of 6,000 volts at 3,000 amps without any difficulty, they're probably the safest place you can plug anything.  (As I understand, the 6,000 volt choice wasn't random... I believe it has do with the largest voltage that gets onto your AC line when there's a lightning strike.)

I used to see a lot of computer power supplies with a particular type of failure.  This was a low-ohm resistor that would go bad from a surge.  There were often scorch marks around it.  Had it happen a couple times to my own power supplies, and I can't even count how many had to be replaced in customers' machines, for the same reason.  That's what we got for relying on those MOV "surge protectors".  Since I began using series-mode surge protection, I don't think I've had one power supply go bad!  (Hard drives still fail, because they have moving parts.)


It may not be glamorous or flashy like a tablet PC, but a series-mode surge protector is probably the single best Christmas gift you could give to anyone who owns a computer, stereo, home theater system, flatscreen TV, or just about anything electrical that they wouldn't want to fail.   Anyone who values their electronics needs one of these things.   (If you really want to do it up right, throw out all the MOV-based power strips throughout your house and replace them with these.  I'm serious.  Then, you won't have to worry about MOV's polluting your ground wire with stray voltages that could kill your other devices.  Ditch the MOV's en masse... you will save money in the long run. )

The SurgeX SA-966 has 8 outlets and is rated for a draw of 8 amps.  This is enough for an average computer workstation, or any other combination of things that draws less than about 760 watts.   Available here, the SA-966 costs quite a bit more than your typical department-store unit, but those can't even come close to this in terms of protection.  The SA-966 will last practically forever, and it's the real deal in terms of being able to stop surges.

The larger SA-1810 has 10 outlets and allows a draw of up to 15 amps, which is the maximum current provided by a standard North American household circuit breaker.  That means you can run just about any piece of equipment through this unit, as long as it can be plugged into a standard outlet.  You can get the SA-1810 through this link

Both units filter EMI/RFI noise, making them great for protecting your vital electronic equipment.  You can get more advanced power conditioning, but that's where you start getting into the $3,500+ units made by Torus Power (they use series-mode protection, also).  

In my opinion, installing good surge protection is one of the best things you can do, not only to extend the life of your electronics, but also for the safety of yourself and your loved ones.  Like they say, "an ounce of prevention..."

I hope you've found this article helpful.  You can help me out by purchasing your gear through any of these links.  Thanks for reading!


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