Electronic equipment repair except computer

For many of us small-business owners, our computer equipment is our single biggest business investment. The data stored on that equipment is frequently one of our most valuable assets--and the hardest to replace completely. Whether we know it or not, both equipment and data are vulnerable to damage or destruction by the very electric power that brings them to life.

Fortunately, with a one-time (or once-in-a-while) expenditure on power-protection hardware, we can greatly reduce that vulnerability. Unfortunately, power protection is a complex subject, and the field is rife with vendors who disagree on key points. Practically the only point they do agree on is that almost any power protection is better than none. In this article, I'll try to clarify the problems, examine the solutions, and some basic recommendations.

Power protection for our computer systems is a lot like auto seat belts and insurance policies: Many of us don't really believe we need them and, given a choice, would rather not be bothered. In fact, we may get along just fine without these things. But we do expose ourselves to risk: the loss of expensive equipment, priceless data, working time, or all three.

SHOCKING TRUTHS ABOUT

COMMERCIAL POWER

It's easy to assume that the electricity that comes from our wall sockets ("commercial power") is safe and reliable because we rarely see any indication to the contrary. For appliances like light bulbs and refrigerators, this is by and large true, but for computers, it just isn't so. Independent studies by IBM and Bell Labs trace a substantial majority of computer failures to problems originating in the electrical power supply. Furthermore, industry experts agree that only a tiny percentage of small-business microcomputers are adequately protected. Most people, it seems, are willing to take adequate steps only after they've been burned.

A tale of two culprits. Part of the confusion about power protection stems from the fact that there really are two separate sets of problems that we tend to lump together.

Let's consider an example: Every time a nearby elevator, air conditioner, refrigerator, or other large electric motor starts up, it draws power away from other electrical devices on the circuit for a moment, creating (to use the most generic term) an undervoltage. If you've ever noticed your lights dim, you've seen this problem in action. When the same motor shuts off, it sends a temporary rush of increased voltage through the circuit. That's overvoltage. The consequences of these two phenomena are quite different.

Undervoltages (sags, brownouts, or total outages) can wreak havoc with computers, because when the voltage drops below a critical level, the computer simply shuts off, even if only for an instant. When this happens, any data that wasn't previously saved to disk is lost forever.

Should a disk drive happen to be storing a file when the power drops, the unwritten part will be lost and the file may be unrecoverable (because it's not properly "closed"). If the drive happens to be updating the file allocation table (essentially the directory) at the unlucky moment, the entire disk may become unreadable. Although statistically unlikely, these things do happen.

Overvoltages (known as spikes and surges), on the other hand, cause physical damage to the computer by overheating its delicate electronic components. A massive surge--lightning is the classic example--can send enough current through an unprotected system to melt components; it can even set parts on fire. Far more common, however, is the constant recurrence of relatively minor surges that cumulatively stress microchips, resulting in their premature failure. According to the IBM study cited above, 75 percent of all computer failures are caused by "electrical overstress" from surges in the power lines.

If you've been thinking "it can't happen here," be assured that while different areas of the country and different working environments experience varying degrees of power problems, none are immune. No matter where you live and work, you are at risk.

Convinced? OK--let's take a look at solutions. Two broad classes of power-protection products are of major interest to owners of personal computers: surge suppressors and backup power supplies.

OVERVOLTAGE PROTECTION:

SURGE SUPPRESSORS

You can purchase a surge suppressor (also called a surge protector) for anywhere between $5 and $200. These days, almost every mail-order computer-supply catalog carries one or more types. The ones that actually do a significant job of suppressing potentially damaging surges start at around $50, list. Reputable manufacturers of high-quality surge suppressors are Panamax (the Max line of products), Proxima, Tripp-Lite (the Isobar line), and Zero Surge (the Surge Eliminator line).

The MOV controversy. Except for Zero Surge and perhaps one or two others, all of today's surge-suppressor makers use half-dollar-sized disks called MOVs (metal-oxide varistors) as their primary surge-stopping components. In simple terms, an MOV functions as a safety valve, "opening" and "spilling" a surge into a different channel (the ground circuit) when voltage pressure exceeds a predetermined limit. While MOVs are inexpensive and do a good job of diverting surges away from your computer, they have two drawbacks.

One drawback is that MOVs deteriorate in the process of doing their job and therefore do it less and less effectively over time. There's no way to tell whether or how much this has happened without professional testing equipment.

Manufacturers of high-quality MOV-based devices contend that adequate component specifications and careful circuit design can mitigate this effect; they claim useful lives of many years for their products. Competitors and other industry experts advise that for maximum reliability MOV-based suppressors be replaced yearly.

The other problem (about which there is more general agreement) is that when dealing with an enormous surge like a nearly lightning strike, MOV-based surge protectors can cause damage to peripherals connected to the computer by data line, particularly modems, fax machines, printers, and local-area networks. Basically, they divert the power surge to another vulnerable part of your system.

An alternative to MOVs. A new breed of surge suppressor, the Surge Eliminator from Zero Surge, seeks to avoid these problems by avoiding MOVs. The Zero Surge unit captures excess energy and "leaks" it at a controlled rate along a harmless path (the neutral wire, not the ground circuit) rather than diverting it in another potentially damaging direction. In terms of surge stopping, the device is designed to meet "worst-case" conditions as defined by industry standard-setting groups. (To be fair, manufacturers of high-quality MOV-based units make similar claims.) The initial cost of a Surge Eliminator is higher than the of MOV-based units (the 7.5-amp model is $149; the 15-amp model is $199), but for people like me with a better-safe-than-sorry bias, the extra security may be worth the extra investment. And over the Zero Surge's 10-year-rated lifetime, it's likely to be cheaper than replacing an MOV-based unit every year or two.

What's in a warranty? Many power-protection purveyors--of MOV-based surge suppressors and other devices--offer lifetime repair or replacement warranties on equipment "properly connected" to their products. Such warranties may testify to the low probability of catastrophic failures, but they shouldn't be taken as absolute guarantees that your equipment and data will be safe. Remember that while someone may reimburse you for that power supply or modem, they're not going to compensate you for lost work or time--potentially far greater costs than the price of new hardware.

Recommendation. George O'Sullivan, an engineer at Abacus Controls, which incorporates Zero Surge technology into some of its own devices, offers some perspective on the question of whether MOV-based suppressors are trustworthy. "A well-designed MOV device can protect you against almost every contingency," says O'Sullivan. "If you want total protection, go with the Zero Surge."

The staff at HOME-OFFICE COMPUTING feel that for most people in most situations, a top-of-the-line unit from Tripp-Lite or Panamax should give both adequate protection and peace of mind. Those living in areas where lightning storms are common, those operating LANs, and those for whom the difference between 99.98 percent protection and 99.999 percent is worth an extra $100 or so should consider investing in the Zero Surge. I talked extensively with Zero Surge developer Wendell Laidley, and I ended up buying a Surge Eliminator for my office. Among other things, I don't feel like worrying about when it might be time to replace tired MOVs.