I am not an engineer, at least not by degree, license or professional practice. I am however fairly skilled and experienced in how electrical and electronic 'wizardry' perform and behave under various circumstances. Common to us all is the problem of bad or erratic power.
If you're familiar with my "modem condom" you'll see one of the simplest principles of in-line circuit protection available for just a few bucks. This device, with some modification, works equally well on some DSL and ISDN circuits also - those circuits are just a different form of phone line vulnerable to the same ill-effects as your simple analog phone line.
For power issues - the A.C. line running to and through your home and to your PC, monitor, printer, external modems, hubs, routers, etc. most people use a $3, $9 or $29 outlet strip with a "surge suppressor" - that's big talk for a $2.00 part from Radio Shack called a Metal Oxide Varistor or 'MOV'. The same MOV device I applied to the modem condom. MOVs work - in specific but not serious cases of power line abnormality much less in cases of lightning or other huge power surges (and with this past year's rolling blackouts in California, and a few storm-induced outages, abnormality is a common thing. You'd think we were living in rural Kansas for crying out loud.)
Believe me - your $6 outlet strip complete with $2.00 MOV is NOT, repeat NOT enough to protect your PC from anything more than the sugres generated by your refrigerator, air conditioner or washing machine.
Why not?
#1 - the average "surge suppressor" outlet strip is just that - a 'surge' suppressor - NOT a lightning blocker.
But if you have serious lightning problems the best thing you can do is disconnect from the power lines or at least put in a huge ferro-resonant isolation transformer
to buffer the surges.
#2 - the MOV used in these things could disintegrate under the surge of a serious power line hit like the pop of an explosive fuse on your local
power line transformer (the 'bang' you hear when a "transformer blows" is usually NOT the tranformer but a 12" long explosive powder-loaded fuse on the power
pole, it's supposed to do that when things get weird on the line.) Forget it helping against a lightning strike.
#3 - your outlet strip has nothing to absorb excess in-rush current when the transformer fuse blows or a lightning spike comes
up the line.
#4 - your outlet strip has NO noise filtering or smoothing to ensure your PC and components see only
nice clean A.C. power.
#5 - your outlet strip has no isolation between your printer, PCs, monitor, etc. so if one of those devices surges on or off, or is
just plain noisy itself, your other components could be affected.
#6 - your outlet strip has only ONE MOV-device across the Hot and Neutral leads.
#7 - your PC's internal power supply does NOT have any over-voltage or surge protection built-in. See that little red slider widget
near the power cord socket that says 115/230??? For proper U.S. power protection the supply should have a 130 volt MOV device in it, but since that
supply is also used in Europe and Asia on 220-240v that 130v MOV would blow up right away. SO why not install at least a 250v MOV for all
PC power supplies? Don't know. There is space on the circuit board for it....
#8 - if your PC's power supply gets hit you might kiss-off any of the following internal components:
OK - this is not Letterman - I do not have TEN items yet - give me awhile.
What I recommend is a commercially-available, SERIOUS alternative or front-end to the $3 dime-store outlet strip - the IsoBar© from TrippLite.
Why the IsoBar?
Depending on the model the IsoBar has at least one and up to three stages of progressive isolation and surge suppression between the incoming AC line and the outlets.
This means that at last outlet set with the highest isolation level, where you should plug-in your delicate PC, virtually nothing bad from the raw A.C. line should get to it - you have MOV surge suppression AND noise isolation, something which also absorbs a little bit of power surge so that the MOV is actually EFFECTIVE in protecting your precious investment.
How effective is an IsoBar?
Look at their guarantee and warrantee - and the amount they are willing to pay you if an IsoBar fails to protect your PC. They mean it. If you're asking if I've ever tried to collect - well, no - the two IsoBars I have protecting servers and workstations here have never failed, where I have seen the ugly results of using NO IsoBar (fried hard drive, LAN card, fireworks from a CPU and system-board - when the PC's supply finally gave up due to latent component - 3-4 days AFTER a power hit.
Check out: TrippLite.com
If you're a techie-type with lots of time on your hands you can try to make your own IsoBar-like protection device. Find at least one if not 2 or 3 dual-pi-type line filters - those little 2x3" sardine-can bricks - the schematic is typically printed on the outside - series inductors in the Hot and Cold lines, capacitors across the line and to ground - for both common-mode and differential noise suppression.
Run the raw A.C. line into the first filter through an adequate fast-blow fuse (forget breakers - they are too slow) and switch to the first filter block. At the OUTPUT of the filter block apply 3 130v 5,000-20,000 joule MOVs - from Hot to Ground, Hot to Neutral and Neutral to Ground. Place an output outlet there - then replicate the circuit (no fuse or switch) to the second and third filter brick and MOV set.
The result is SIGNIFICANT, MASSIVE filtering to the third stage, very robust MOV surge suppression for any and all possible inbound power hits, and piece of mind.
Don't forget REAL GROUND!
If you have a more or less modern home with a real dedicated continuous Green wire ground from breaker box to every outlet you're in pretty good shape.
If your outlets get their ground from the conduit pipe or metal jacket of spiral 'BX' metal-wrapped cable do not trust it. If your outlets are in plastic or bakelite boxes with NO ground wire of any kind you're in trouble. (You're probably plugging that 3-wire outlet strip plug into a useless 2-wire adapter) I once did a safety investigation of the electrical circuits supplying medical equipment at a medical facility in Chicago - it was 'OK' for lab and patient equipment to depend on 7 stories of old metal pipe and raceway for ground without a SOLID ground wire from Earth to anywhere. YIKES!
Do not trust your interior cold water pipes for ground unless you know them to be copper from faucet to street...iron pipe anywhere in the plumbing system is a disaster waiting to happen, iron and copper mixed generally means that some part of the system is ISOLATED from ground - iron/coper plumbing uses a galvonic junction device which intentionally defeats continuous metal-to metal contact between the two pipes - NOT good.
Run a dedicated ground wire from your house ground post (by the electrical box) or a newly installed ground rod near your computer stuff. With conduit or BX ground you're asking for a little trouble making your newly-added ground do double-duty to back-protect the rest of your home; with no ground your PC stuff will be OK and not protecting the rest of the house.
Without a solid reliable ground some aspects of any outlet strip are useless. Any or all of your electrical devices could be lifted several THOUSAND volts above ground during a lightning strike. OUCH!
That's all I have - IsoBar or nothing!