Dan's Data is without equal. Here he tackles surge suppressors. He puts in one place everything I've picked up over many years, and then adds much more. His discussions always remind me of how much we lost when BYTE went under.
We have 3 PCs and 1-2 laptops in our home, not to mention thousands of dollars of other voltage sensitive gizmos. I like the idea of having an electrician install a whopping big fusebox conditioner; OTOH it may be less trouble to buy $50 suppressors and replace them every year. I wish Dan would provide some examples of vendors he likes.
...No ordinary cheap powerboard ("cheap" definitely includes "$US100") actually provides very good protection from line current gremlins...Cheap surge filters are all based around components called Metal-Oxide Varistors (MOVs). MOVs pass current only when the voltage across them is above a set value, and they react to overcurrent in microseconds. A circuit breaker or fuse can take tens of milliseconds to trip or blow; that's much too slow for spike suppression.
Unfortunately, MOVs will only work a few times, at best. The more work they have to do, the closer to death they come...Better surge/spike boards are meant to tell you when their MOV's died via a little light or even a buzzer, but they commonly, actually, don't. A surge/spike filter that's been in use for some years and still reports its MOV as perfectly healthy is, probably, lying.
Better surge suppressors use two other kinds of spike-sinking component. Gas arrestor tubes are much tougher than MOVs, but respond too slowly to be useful for many applications, including computer protection. But they're present in better power filters because they can handle the load of a really big surge, after some other component has (possibly) bravely given its life to intercept the first several microseconds of overvoltage.
And then there are Silicon Avalanche Diodes (SADs), which are between gas tubes and MOVs in toughness, but as fast as a MOV. They're more expensive, though, which is why cheap surge/spike filters never contain them.
The best surge/spike suppressors gas arrestor tubes and SADs, and possibly MOVs as well. Proper "power conditioners" go on to include a great big heavy iron transformer, whose 50Hz resonance (60Hz, in countries that use that mains frequency) and enormous inductance blocks surges and spikes quite well too. This makes the power filter large and heavy and easily as expensive as a mid-range Uninterruptible Power Supply (UPS), but if there's an aluminium smelter down the road from you, this is the kind of filter you want. Rather than faff around buying tons of flaky powerboard filters for all of your electrical outlets, you should get an electrician to install one giant power conditioner at your fusebox; now, the whole house should be bulletproof.
... The take-home message from all of this is that quality power filtering isn't cheap. Fortunately, though, most people here in Australia don't need quality power filtering. To Aussies, I therefore say: Go ahead and buy dirt cheap no-CEW filter-boards, and be merry.
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