On ES550, Do All Outlets Have The Same Surge Protection?

[BillP]

This question was originally posted by Larry on APC forums on 6/17/2017

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Yesterday I realized my router was plugged into a Surge Protection outlet, and had been for 6 months or so. I moved the router to the Surge Protection Plus Battery Backup side. Well, about 4 hours later, a thunderstorm moved through and my router got fried. No damage to anything else. I assume it was a surge, but we didn't have any indication that we had a surge, we just lost our internet. Was that just freakish luck, or is there some reason my router my have received less protection than it had gotten for the last six months or so, when it was plugged into the surge only side?

[voidstar_apc · Accepted solution]

This was originally posted on APC forums on 6/18/2017

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All outlets use the same surge protection electronics, however the battery backed outlets are disconnected from the line (on battery) during a power disturbance conferring additional protection in some circumstances. Additionally, coax and other communication cables going to the router can provide a path for surges if the other end is unprotected. So it's hard to say.

There are two damaging parts of a lightning strike: the initial strike (affects those close to the strike) and restoration of power after the strike (affects a wider area). Whether anything, even surge-protected and on battery, survives a lightning strike close to the house comes down to luck because it's a lot of energy and can bypass the protection elements. Restoration of power can result in higher voltages (a surge) for a short period of time like water rushing into a dry stream-bed. Surge protection is effective protection for this.

[BillP]

This reply was originally posted by Larry on APC forums on 6/18/2017

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Thanks for the reply voidstar. I guess it was just dumb luck that I happened to change the router outlet and it got taken out on the same day. I just wanted to know for possible future decisions on whether I wanted to plug something into the battery backup side or not. Since nothing else gave any indication of a power surge, your suggestion that it came though the router input signal makes the most sense. Thanks again.

[wagnerlip_apc]

This was originally posted on APC forums on 6/18/2017

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Most of "surge protection" system is basically made by a simple electronic component (Varistor, MOV = Metal Oxide Varistor) that conducts electricity when the voltage on its terminals goes higher than a specified value.  The component short circuit its terminals, absorbing "most" of the over voltage.   Yesterday I tried to fix some APC units, and saw some using several (6 or more) varistors  in parallel with the power outlets, others use less varistors.  What happens is that once the varistor "absorbs" the peak voltage, it can damage itself, or pre-damage but they can cook themselves at once or the next time they absorbs energy.  

It means two things:  1) It may protect your equipment for an over voltage peak and survive for next over voltage; 2) It may protect your equipment and die in the process, not protecting anything any longer.

Solution?  Two options: 1) install a lower cost surge protector between the wall power outlet and your APC unit, so, after an electric thunderstorm and close by lightning strike, smell your low cost surge protector - if it smells burned, even if small smell, put it away and install a new one.  The smell means it burnt the protection; or, 2) Open the APC and replace the burnt varistors (normally they are sky blue or peach color, when burnt they present a black face) every 6 or 12 months.  This is way they install 6 or more varistors, so some still protecting after others already fried in the process.

Remember, cheap surge protectors use less varistors, sometimes just a couple, what is enough for just one lightning strike.  You can always purchase varistors at eBay or Digikey, Mouser, etc, and install more in parallel with the ones on cheap surge protectors.  They are sold specified by voltage they should act.  If your wall voltage is 115Vac, you can purchase varistors for 180V or close to it.

Also, when connecting two surge protectors in series you increase the protection, because you are adding more varistors in parallel, to act in case of a over voltage peak.

Varistors may protect against a lightning strike in the neighborhood, but they will protect absolutely nothing if the strike hit your house of the ground around your house. A strike offers over voltage of millions of volts, it will be just a matter of luck and chance for your equipment survive a strike like that.

There is a different component from a varistor that can survive several strikes, more expensive, only used on professional surge arrestors.  There is also a glass capsule containing a special gas, it is installed at the main power entrance of your home, in case of a higher voltage peak, the capsule conducts electricity through the gas, arresting the peak.  It was more used in the past when Varistors were not developed yet.

Wagner