Are surge protectors on the main power supply actually needed in
here in the UK we have few overhead mains power lines and have a
relatively steady mains power supply when compared to many other
countries (including the US).
However there seem to be very many surge protector products
advertised for sale in the UK (Argos, Maplins, etc).
I am quite sure it is not bad practice to use a surge protector but
in fact I have never known anyone who has has a problem from a
surge coming in through the power supply.
So personally I don't bother using a surge protector on my PC.
Am I being too complacent?
Lots of people run a particular OS which is known for its
instability, and you can sell them just about anything if
you suggest it might make their systems more stable. Of
course it doesn't, but that just means they'll try something
else (except changing the OS;-). Surge protectors are one of
the many items on the list that such people will try.
The other issue is that the multi-way trailing socket blocks
got down to the point where they're only a couple of pounds
each, or even less. By adding a extra few pence worth of
components, you can call them surge protected and sell them
for 3 times the price. Brings in more profit.
True. Even if you have millions of pounds worth of equipment
on your supply, it isn't worth it, the occurance is so rare,
so it certainly isn't for a few home PC's.
What I have seen several times is damage caused by a surge
induced by lightning on a phone line. Of course, the mains
surge protector will do nothing to protect against that.
Not in my opinion.
If I saw something at less than rip-off prices for protecting
against surge on phone line, I might consider that.
Is the cumulative effect of transient voltages leading to premature
equipment failure not an issue then?
something as simple as a desk fan switched on & off and supplied via the
same socket as a PC can create a transient over voltage of 1kV
Sure it will not knock the PC out but it will reduce the life of the kit.
I have a surge protector which includes protection for the phone line,
so that's where the ADSL modem gets plugged. Whether it would actually
work or not is another matter of course. My complacency lies in not
bothering to research the matter thoroughly, on the grounds that if I
was buying snake oil, it was at least *cheap* snake oil...
For the mains, online UPS is the proper solution, but I can't say I'm
unduly concerned about not having one. Power provision in the UK is
fairly reliable at the moment, although political and business
imperatives will probably conspire to make it worse in the future.
A plug-in surge protector is on the order of tens of times
more money per protected appliance. Furthermore it does not
even claim to protect from the typically destructive
transient. Protectors do not stop, block, filter, or absorb
destructive transients. Ineffective protector manufacturers
get one to wish that is how they work. In reality, the
protector is not protection. Protector and protection are two
separate components of a surge protection system. Effective
systems must include the protection. And the connection to
protection is either a hardwire (less than 3 meters) or a
protector (also part of a less than 3 meter connection).
In short, the protection is called single point earth
ground. Destructive surges may enter the building seeking
earth ground. If not earthed (either by hardwire connection
or by surge protector), then the destructive surge may find a
path to earth ground via computer. One classic example is due
to a direct strike to lines highest on utility poles - AC
electric. Incoming on AC electric, through computer and its
modem, then outgoing to earth ground via phone line. Many
then *assume* the surge entered on phone line, damaged modem,
then stopped - a violation of even primary school science.
Effective protection means all incoming utilities are
earthed before entering the building. All must be earthed to
the same single point earth ground. That means even the CATV
wire drops down to earth ground, connects ground block 'less
than 3 meters' to that earth ground, and only then rises back
up to enter building. Again, no surge protector required
because earthing is accomplished by a direct and short
These concepts are explained further including some examples
of 'whole house' protectors for AC mains at:
"RJ-11 line protection?" on 30 Dec 2003 through 12 Jan 2004 in
"strange problem after power surge/thunderstorm" in
comp.dcom.modems on 31 Mar 2003 at
Additional information on how surge protectors work, how
they are rated, installed, etc was posted in:
"Opinions on Surge Protectors?" on 7 Jul 2003 in the
newsgroup alt.certification.a-plus at
"Power Surge" on 29 Sept 2003 in the newsgroup
One industry professional demonstrates how two structures
are protected. Notice every wire entering each structure
(building and tower) must first connect to single point
ground. Even the buried phone wire carries a potentially
destructive transient which is why even buried wires must
enter building at the service entrance with the 'less than 3
meter' connection to earth ground:
How do we identify ineffective protectors? 1) No dedicated
connection to earth ground AND 2) manufacturer avoids all
discussion about earthing. A surge protector is only as
effective as its earth ground - the protection.
Those ineffective protector manufacturers fear you might
learn about the essential earth ground AND discover that
plug-in protectors cost tens of times more money per protected
Could a very fast-acting switch (like in an Residual Current
Detector) be used to cut the incoming power supply quickly enough
to halt the transient mains electricity spike before it got to be
Again an assumption that something will stop or block a
destructive transient. Kilometers of air could not stop the
transient. Do you think that silly little RCD switch contact
will do what kilometers of sky could not? Again, protection
is about shunting (diverting, connecting, shorting) a
transient to earth ground. There is no way around that
fundamental fact. Nothing is effective at stopping such
Again, read those cited discussions. Effective protection
was even demonstrated by Ben Franklin in 1752. It too is
discussed there. Did Franklin stop or block transients? Of
course not. Only products selling on myths attempt to get
others to "speculate" that protectors work by sitting between
the transient and its objective - earth ground destructively
via a computer.
Second - what fast acting switch? That RCD maybe takes 10
milliseconds to respond. In the meantime, 300 consecutive and
destructive transient would complete before the RCD even
thought about tripping. That fast acting switch has the speed
of molasses. Effective protection is defined in those
previously cited posts. You have much to learn there.
Haven't had anything break that was plugged into it, although the power
has flickered or quit many times during storms. But then, the TV and VCR
are still working, and they're not on a surge protector.
"Let us learn to dream, gentlemen, then perhaps we shall find the
truth... But let us beware of publishing our dreams before they have been
I've been around for some time now, and I've never known or heard of anyone
actually collecting on such an offer. I know a few that tried, but gave up
after about the fifteenth hoop (getting through the first few was a cake
walk, but they kept getting higher, and higher!). :-] I've heard that
some outfits will pay claims depending on the cost of the item involved, but
know damage will occur with their devices, and consider the payout a cost of
Read all the fine print on the offer you have, and report back if you think
you still have a prayer collecting after damaging surge event.
Remove the two fish in address to respond
firstname.lastname@example.org (Gregory L. Hansen) writes:
If you do the sums, it cheaper for them to leave out the surge
suppressor components altogether and just pay up on any such incident.
Power line surges (in the UK at least) is a vanishingly insignificant
source of damage.
Yes, we've had an exceptionally stable/reliable supply in the UK
for perhaps 30 years now (or well over 40 years if you ignore the
1972 miners strike). There are a number of reasons why that's
unlikely to be maintained in the future though.
In a nutshell...
o We are no longer self-sufficient in energy (became a natural gas
importer last year) and are increasingly going to have to rely on
sources from the less stable parts of the planet and sources
which require traversing the less stable parts of the planet.
o All the non-natural gas sources of generation are winding down
at the end of their service lifetimes, and no more being built
(ignoring renewables, which are currently insignificant).
o We no longer have a store of energy -- we used to have many months
supply of coal stockpiled at power stations and weeks supply of
gas stored in gasometers -- all now gone.
o We now have very little in the way of spare generating capacity.
The nationalised electricity generating board used to maintain
spare capacity to enable peaks and unexpected outages to be
handled without concern, but the privatised companies mothballed
this plant as they are only paid for what they produce. It
would take between 3 months and a year to get it back in service,
depending how long it's been mothballed, so it's no use as an
The industry had a wake-up call on 10 December 2002 when the country
got within a couple of minutes of having to load shed (switch off
parts of the country in an emergency due to not enough power being
able to be generated to meet demand). In spite of this, nothing was
done. Again last winter, there was a particularly cold spell forecast
and a number of experts warned we were in an even worse state than
the year before. Fortunately, the cold spell wasn't anything like as
bad as forecast. Given these wake-up calls have been ignored by the
government, it looks like it's going to have to get worse before
any notice is taken, and we probably are going to have to suffer a
significant load-shedding incident blacking out significant parts of
I have no UK electrical power system knowledge.
I do however have extensive electrical utility knowledge.
I would never install a computer without a UPS.
What is the age of the installed cables? When a cable faults the surge is
Transformers, capacitors, breakers, generators ...all fault at times and
they result in heavy electrical surges.
HDD are frequently corrupted due to power events.
~$40 USD (350VA) with $15000 of equipment insurance is worthwhile.
References, no, practical, hands on experience, yes. I've seen this
several times, not only the HDD, but I've had transient power problems
take out motherboards too.
Case 1: Home computer (this one) tree fell across a main line (11kva I
think), caused a surge prior to the stepdown transformer kicking out,
corrupted an almost new 40 gig hdd. Fortunately, an LLF fixed it.
Case 2: Engraving lasers at work, fed from the bus, kept killing HDD's
and motherboards. Ultimately traced to transient voltage spikes,
installed an AVR UPS. Failures were occuring once to twice a week, after
the AVR UPS was installed on each machine, we have had Zero failures, in
over a year.
You can't 'idiot proof' anything....every time you try, they just make
Hard drives can be corrupted for various reasons based also
upon what the filesystem is. For example, if using FATxx
filesystems, then a loss of electrical power at the right time
can even erase files from that drive. Just another reason why
the technically informed want NTFS filesystems on drives; not
Transients should never be a problem to disk drives or
memory. Based upon how these devices are connected, then a
differential type transient would be required to cause
damage. But all minimally acceptable power supplies must have
the essential function called overvoltage protection - that
makes a differential transient not possible.
That is the theory as well proven by power supplies even 30
years ago. Reality is the gross profits obtained by dumping
inferior supplies in North America where so many computer
assemblers don't even have basic electrical knowledge. Many
clones are not built and sold missing the essential
overvoltage protection because the assembler only understands
one specification - dollars. It's called a bean counter
mentality. If the power supply is sold on the cheap, (ie full
retail price is less than $60), then this and other critical
functions are simply *forgotten*. Does not matter. Consumer
is only to be fleeced.
If the destructive differential transient does occur, there
is no overvoltage protection circuit to protect that hardware
- do to power supply purchased by a bean counter. No
problem. Myth purveyors then quickly blame speculated surges,
and recommend overpriced, typically undersized, and
ineffective plug-in protectors.
Up front - does the power supply specifically state that
overvoltage protection is provided? If not, then it probably
is a man-made disaster just waiting to destroy disk drive,
data, and other computer components.
This overvoltage protection is something completely
different from another disk drive threat to FAT filesystems -
blackouts and brownouts.
Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here.
All logos and trade names are the property of their respective owners.