[RndTbl] Power bar/surge suppressor

Hartmut W Sager hwsager at marityme.net
Mon Jan 29 11:59:46 CST 2018

Oh, I forgot to mention:  The fine print on practically all "lifetime"
guarantees stipulates "original owner only" and "purchase receipt
required".  That includes "lifetime guarantee" car batteries too, which are
additionally restricted to "vehicle originally installed in".

Hartmut W Sager - Tel +1-204-339-8331

On 29 January 2018 at 11:42, Hartmut W Sager <hwsager at marityme.net> wrote:

> I'll weigh in with 3 decades of (some) knowledge here, having studied and
> sold these things once upon a time.  First of all, the insurance and the
> actual performance/reliability are totally separate, though both are
> typically higher as the price rises.
> Above a certain price point, it became fashionable to offer insurance as
> described by Rob below, but this was for marketing purposes, and, like all
> insurance, is based on a statistical gamble.  I.e., a few cases will arise
> where someone's equipment behind a surge suppressor (no matter how good)
> gets damaged, and the suppressor company or the insurance company involved
> can statistically afford to pay those in the overall income/expenses
> picture.
> Trevor's tech comments are completely correct.  There is no natural
> time/usage-based wear-out of any of the components, but they can wear more
> if the stresses (surges, etc.) are more frequent or more intense, and many
> models may indeed need to be replaced after a lightning strike nearby or a
> nasty surge.  Some of the better models try to self-identify (and alert you
> to) failure/end-of-life.
> Now, back to the original power bar question.  As for the actual
> components, virtually all power bars up to about $50-70 use nothing but a
> pile of MOV's (metal oxide varistors), which look just like simple
> thin-blob capacitors.  The price of the power bar determines how many MOV's
> are used and how much surge each MOV can dissipate (hence a joules rating
> expressing how much energy can be dissipated in a very short time), and the
> price also determines whether only the hot-to-neutral voltage is protected
> or also the hot-to-ground voltage.
> MOV's are rather crude devices that usually "clamp" above 300V (120V AC
> peaks around 170V), so they are quite unsuitable for low-voltage surges of
> longer duration, but they are excellent for extremely short high-voltage
> surges, especially since they (MOV's) have an extremely quick response
> time.  Longer high-voltage surges will of course fry the MOV's.
> Higher-priced devices, beyond the typical power bars, use all kinds of
> additional components beyond MOV's, and thus can have much better
> characteristics all-around.
> Hartmut W Sager - Tel +1-204-339-8331 <(204)%20339-8331>
> On 29 January 2018 at 10:12, Rob Guderian <rob.guderian at gmail.com> wrote:
>> Some surge suppressors say on the box that they 'guarantee' it, and
>> make it sound like they will replace your equipment if it fails to
>> suppress the power surge. I haven't read one in years, but I believe
>> they do have a limited amount of time they [would/might/should] be
>> willing to honour that guarantee.
>> Advice: Look for it if you're buying one. The cheaper ones definitely
>> don't have one, the better ones should.
>> On Mon, Jan 29, 2018 at 3:10 AM, Trevor Cordes <trevor at tecnopolis.ca>
>> wrote:
>> > On 2018-01-28 Kevin McGregor wrote:
>> >> Hey, what's the prevailing opinion on power bars with built-in surge
>> >> suppressors? How long do they last? Should they be replaced every,
>> >> say, 5 years?
>> >
>> > Never heard of a lifespan for those things.  I'm an APC partner I'm
>> > sure that they would have been blasting that in all their emails and
>> > "APC Currents" mag, etc, all the time if that had been the case.  Also,
>> > would make their lifetime warranties on their good surge bars a bit
>> > silly.
>> >
>> >
>> ​​
>> The only thing I've ever heard is replace them after a lightning strike
>> > nearby or nasty surge.
>> >
>> > Then again, you made me think about it and perhaps the passives in
>> > these things could wear out with old age??  I'm pretty sure there's no
>> > electrolytic caps in them ;-)  and there's not much heat generation,
>> > so all the other passives that could be in there should last like 30+
>> > years like 80's computers have.
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