Aloha everyone. We just had our second earthquake of the month here, and so this topic naturally follows. Would like to know if there are any users of series surge suppressors (like Brickwall) and if you thought the extra expense was worth it. Following is a response from BrenR to a question I asked concerning line conditioning and surge suppression. Alan had originally recommended I contact BrenR, and his advice was quite helpful:


There's a pretty major difference between computer equipment and audio equipment, basically in the power supply on the computer. I've never heard of audio equipment, pro or consumer, being damaged by power sags outside of, say, tape getting caught in VTR parts in some cases. Power loss really isn't much of a threat to solid state electronics... it might munch up VHS tape or something to that effect, but it's not going to, say, fry a transistor or anything.

Computer power supplies are quite a bit more apt to cause secondary damage to computer parts. When you dump power and immediately restore it to an AT or ATX power supply, they have a tendency to spike the DC voltage lines - there are 12v, 5v and 3.3v lines running out of them to the necessary places (12vdc & 5vdc to the drives, 3.3vdc to the processor - core voltages vary by manufacturer and chipset, but it gets sent 3.3). The power supplies in computer cases are really easy to cause to fail to regulate. For instance, I scratch built an arcade machine, and was going to use an AT power supply from a computer to power a few cooling fans and the coin reject lights. I had serious issues getting it to work at first before an EE friend pointed out they need a minimum load to regulate. With only a #44 lamp connected, the power supply output on the 12v legs would swing wildly between ~0v and ~50v. That's why you get issues with computers. A similar thing used to happen very often with the old AT computer cases, the rule of thumb was to shut off the case and NOT turn it back on until the fans stopped... rapidly flicking it on and off would blow something up maybe 1 in every 200 times.

There are a few different protections - good UPSes (uninterruptable power supplies) that you get for computers mostly provide boost and buck protection for mains voltage. That is, if power comes in low, it will boost the voltage going to the load via a power inverter and the onboard DC (usually lead-acid) battery. If the mains is coming in hot it will buck the extra voltage away to ground. A bunch of ways this is done, some always have the power inverter in the circuit... so you're always running off the battery while charging it, some will only kick in when necessary - for your needs, that's as in depth as I need to go I think. My personal opinion is that for HT equipment, it's mostly for convenience (no blinking 12:00) and peace of mind than actual protection. Voltage sags aren't a big enemy, and we can fix voltage spikes an easier and cheaper way (more in a second)

Surge protection - this IS a good idea... power sags aren't a big problem... power coming in hot is. Get yourself a power bar - yes, those ugly white things behind every computer desk. Get a good one... maybe made by Fellowes or another brand name... maybe something in the $15-$20 range... and it should have a lighted on-off switch. Ever seen an on-off switch on a power bar flicker? As they get more damaged, the light will be "off" longer when it does... some of my older power bars in my video lighting kit have been damaged to about 5%-10% of their original life, being run off generators, and on circuits with HMI lighting, etc. These work very simply - hoping you understand basic alternating current theory - there are MOVs - metal oxide varistors - attached between the hot and ground legs. But wait, that's a short circuit? That's the beauty of the MOV... under normal voltage conditions, the electrical resistance across it is very high, as if it isn't there at all (say like a piece of nonconducting plastic), and power flows normally through the circuit and not down the MOV to ground. Under extreme voltage conditions, the MOV's resistance drops so it looks more like a piece of wire, and the voltage is shunted to the house safety ground. Problem is, MOVs are sacrificial, every time they activate like that, they give a little bit of themselves... and in good surge protectors, that's what makes the power light flicker. Once it's fairly noticable, it's time to change out the surge protector. So, that's my opinion in a nutshell. Feel free to ask any follow ups.