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Surge Protection When Switched Off

Hello experts.  Do surge protectors protect at least as well when switched off as they do when switched on?  I would think that any surge would be stopped at the switch, but then again I have read that unplugging is the ultimate protection.  Once the switch has been breached, I can well imagine that whatever crimps a surge inside the surge protector needs to already have voltage applied to work.
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NonComposMentis
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NonComposMentis
4 Solutions
 
Esteban BlancoPresidentCommented:
The surge protector will only work when it's on.  Best way to do it if you need to leave things off is to unplug it from the wall.  You can get a surge and it can cause damage.

If the surge protector looks "iffy", get another one.
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Frosty555Commented:
From what I know about surge suppressors, the electronic components that provide the surge suppression are passive - they do not require power or require electricity to work, they rely on the physical characteristics of the materials they are made out of to suppress the surge or spike. For example, a metal oxide varistor is a semiconductor that will change resistance depending on the voltage applied to it - this is not something that requires a separate power source, it's a physical characteristic of the material.

So I would say no - a surge suppressor works just as well if it is turned off than if it is turned on.

However, that being said, I agree with you as well that any small surges would not make it past the switch of the power bar was switched off anyways. Not unless the surge or spike was so strong that it arced across the switch. But a surge that powerful would probably overwhelm the surge suppressor anyways, though so it is irrelevant whether it was turned on or not.

As you have read, simply unplugging the device physically and fully disconnects BOTh power wires (hot and neutral) from the power source entirely, and provides the most amount of protection.
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Esteban BlancoPresidentCommented:
Well there you go.  Sounds legit.  Some of my things at home where zapped during a vacation when they were off (didn't want things like TV and other components to turn on and waste electricity while we were gone) and sure enough, they got zapped.

Now I have a whole house surge protector.  Lesson learned.

Cheers!

Esteban
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Frosty555Commented:
Yeah I was going to say as well - the cheap "power bar surge suppressors" you get from a retail store are not designed to protect from a lightning strike. They're designed to protect from the small fluctuations in voltage that come from the utility company or that are caused by high-current devices and motors in the house turning on or off.

A surge protector will not hold up against something like a lightning strike. Switching the powerbar off will also not necessarily protect you from a lightning strike (a high enough voltage will arc across the switch). If you want to actually be fully protected, you have to physically unplug it from the wall.
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nobusCommented:
surges and lightnings can cross gaps - if powerful enough
small ones can be handled by the cheap protectors
so  - a small switch will provide a better protection than a surge protector, but since it has a small gap -  can be crossed also.
removing the power cords will provide a MUCH larger gap - hence the best protection
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Gary CaseRetiredCommented:
Surge protectors work just as well whether they're on or off => they protection does NOT depend on the state of the power switch.    HOWEVER ... note the "just as well" part of that comment ==>  a cheap, ineffective surge protector (i.e. a typical power strip) will work "just as well" whether it's on or off ... in that case, not so well.    A hiqh quality unit, like a quality UPS with AVR, will work FAR better ... again, whether it's on or off.

I've seen a couple of APC UPS units that were totally destroyed by a very large surge from a lightning strike on a home -- but NONE of the connected computers were damaged ... neither those that were on; nor those that were off.
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NonComposMentisAuthor Commented:
With such a rich set of expert opinions, awarding points is definitely going to hard.  Frosty555 deserves the most, as s/he was first with what emerged as the consensus opinion PLUS had the a plausible theoretical explanation.  Everyone else provided either additional understanding or real-world examples, and so the remaining points were distributed evenly among them.
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