grounding outlets for computer equipment

A guest appearance by one of my favorite people -- my husband! He became rather knowledgable about old wiring during the process of rewiring our kitchen and adding outlets throughout the house. I am incredibly thankful he undertook this project, because the only thing I want to do is plug in my hair dryer and not have it shut off all the lights in the kitchen, dining room, and bathroom. Yes, that's what happens when you have one circuit for all of these things.

One electrician looked at me like I was crazy when I explained I wanted properly grounded outlets for my computers.

"All the kids up at the University just use cheater plugs. Works for them," he added.

"Yes, that's why their hard drives die after a year," I retorted.

I didn't hire him.

I called up another electrician to get an estimate on running a few new circuits. He said he could ground the existing outlets.

"How?" I asked. "The wiring is old two-wire Romex, not metal conduit. There isn't a path back to the box other than neutral. Grounding to a water pipe is not code. Are you going to run a ground back to the box?"

He explained it was a trade secret, and he wouldn't tell me how because I would tell other people or just do it myself.

Didn't hire him, either.

There are two reasons a grounded outlet is a necessity if you care about your computer at all. The first and most important reason is surge protection. The electricity in your house is very noisy. There are small variations in current and voltage *all the time*. Your computer contains components which are very sensitive to these fluctuations, and over time, plugging in to a poor electrical source will degrade these components. A surge protector is needed not so much for catastrophic events like lightening strikes, but for these everyday small surges.

Do your lights flicker when you turn on your vacuum? Having your computer on lines shared by motors is a particularly bad idea, because starting and stopping these motors create power fluctuations on the line. (This is a topic for another time.)

All but very very high-end (e.g., costing $250) surge protectors operate by directing overcurrent to ground. If you do not have an equipment ground, there is nowhere for excess voltage to go, and your protector is useless. This is why using a cheater plug to plug a three-prong power strip into a two prong outlet makes it useless as a surge protector.

As an aside, I note that the previous owners of our house replaced all the two-prong receptacles with three-prong ones, but since there is nowhere to connect the ground in the existing wiring, these are not grounded. I should note that this is both illegal and a bad idea. I will return to this in a later post.

The other reason electronics should be plugged into a properly grounded outlet is to keep the metal parts at the same potential as earth. Otherwise, current might flow if these components come into contact with something which is grounded. However, this reason is far less important than having good surge protection.

Many people misunderstand the fundamental reason for the third ground wire. It is connected to earth back at the box, either by your service being bonded to a rod buried in the ground or by being bonded to your water pipe where in enters the house, and will direct an extreme event such as lightning to earth. However, its more fundamental purpose is to provide a *low resistance* independent path back to the box. The exposed metal in your appliances should be bonded to this path through the ground wire. Should the insulation break down and these surfaces become energized, they will pass through the ground back to the box, hopefully tripping the overcurrent protection (fuse or breaker). Otherwise, if you were to become grounded and come into contact with the energized appliance, the current would flow through you.

The real estate agent had recommended installing a GFCI, either at the outlet or one at the beginning of the circuit, to take care of grounding the computer. This doesn't address the problem at all -- the GFCI prevents you from getting electrocuted in the case of a ground fault, but doesn't protect your equipment at all.