Power Protection

I've written before about power outages, surges, brownouts, etc. and the problems they cause for information technology and the people who depend on IT (i.e., everyone). Check it out.

Unfortunately, for political reasons, these problems are not going to be resolved in our lifetimes. So, today I have some practical advice for dealing with one of the power issues that you and I will encounter -- transient fluctuations in power, which are commonly refered to as power surges, spikes and dips. (Spikes contain high voltages but usually last only a few milliseconds, as opposed to longer, but lower voltage power surges.)

Following a thunderstorm which passed through our area last week, our shop experienced a "surge" of repair business (data recovery) from people and businesses whose computers were fried by the storm. How can we help people avoid these catastrophies?

In the United States, the Alternating Current voltage standard oscillates between +120 volts, through 0 volts, to -120 volts at a rate of 60 complete back-and-forth cycles every second.

Power fluctuations outside the norm can happen for many different reasons. For example electrical appliances and equipment cycling on and off can cause transient dips and surges. However, minor fluctuations are not a problem for most modern electrical equipment. For example, all but the cheapest computer equipment has the capability to handle transient power surges. And such equipment handles transient dips in voltage by drawing more current (amps) to deliver constant power (watts).

Placing a surge protector between your electrical equipment and the wall plug generally does you no good, except if your equipment has no ability to handle surges. On the other hand, there's no sure way to know if your equipment has that capability short of opening it up and looking for Metal Oxide Varistors (MOVs) inside (most brand-name and business-grade PCs have MOV's in their power supplies).

Unfortunately, a false sense of security is not the worst-case scenario for connecting your PC, for example, to a surge protector. Depending upon the design of the surge protector, voltage surges and spikes on the phase wire will be dumped to either the neutral or the ground wires or both. Depending upon the size of the spike and local variables like the specs of the premises wiring and the distance to the earth ground, the (diverted) surge may travel to the PC through the neutral or the ground wires. If a diverted surge reaches the PC, bypassing the PC's surge protections, frying the PC, the surge protector ironically will have caused the PC's demise.

In the event of a thunderstorm, where the electrical potential of each lightning bolt may be 100 million volts, and each bolt can carry 50,000 amps of current, it is impossible to predict how currents will flow in the vicinity of a lightning strike.

So, even if your electrical equipment is turned completely off, it may be damaged in a thunderstorm if it is merely plugged in. That is because with all those volts around, the current can arc over the small distances separating the wires inside your surge protector and/or your electrical equipment. And, the spike can travel from anywhere; the air, the earth, the ground wire, the phone line, the cable TV line, the computer network lines, etc. And we're not only talking about the effects of a direct lightning strike. These effects can be caused by a lightning strike on a utility pole miles away or a tree down the block.

In conclusion; how do you protect your valuable electronic equipment from transient fluctuations in power, which are commonly refered to as power surges, spikes and dips? Dips are not a problem. Surges are not a problem. Spikes are a problem and there is nothing you can do about them except to unplug all your equipment in the event of a thunderstorm in your area.

This is an unresonable prescription for most of us. What if we are away from our home or office when the storm hits? Then all we can do is carry insurance to cover our losses if our equipment is fried. Insurance will generally not cover the value of data lost, so, archive your persistent records to permanent media (DVDs) and backup your dynamic files regularly to online, offsite storage.