Tuesday, June 04, 2002

Household power problems

Unless you can borrow an ex-spouse's car, here's another thing not to do at home. Wind up the engine in the car while in Neutral, then shift it into Drive (or dump the clutch into high gear) suddenly. Did you notice anything?

Well, people are everlastingly doing the equivalent to our electrical supply system. And your house's wiring feels those sudden changes or "transients", passing them on to your appliances.

Just as some things are more fragile than others, some electrical equipment is more sensitive to transients than others. Big strong dumb things like heaters can take about anything. But devices containing chips are especially sensitive - transients can destroy the physical devices or just the data these devices contain. Even light bulbs are sensitive to transients - have you noticed that they usually fail the instant you turn them on?

Once I was driving in rural Illinois when I saw a very bright flashing in the distance. I was already going that way and I had nose troubles, so I drove toward it. About 15 miles later I found the problem - a power line had broken loose from the welding shop it supplied and was flopping about on the ground. Those flashes were momentary short circuits, and every one of them would have felt like a big impact on the devices downstream. Anyway, a bunch of people were standing there watching it jump and flash and make noises. Fortunately no one was stupid enough to fool with it.

You can protect yourself from the power company and your neighbors in various ways. After frying her PC's motherboard, a relative is going to have the utility install some power conditioning apparatus for a fee of about $6/month. Or there's other equipment available from companies like Smarthome.

The above protect the whole house. But that doesn't mean that you don't generate transients yourself. Bump the garbage disposal. Turn on a light. Turn on a power saw, refrigerator, or air conditioner. Anything with a motor might take as much as 6 or 8 times as much current when it starts as it does when it has come up to speed - maybe you even see the lights dim when some of them kick on. For this reason it is smart to use surge protectors and uninterruptible power supplies.

Surge protectors are easy to find, but realize that they don't last forever - each spike damages them a little until they can no longer help. As for UPSs, I wouldn't be without one. They have the added virtue of alarming if the voltage coming to them from the wall gets low, so you have some warning about impending brownouts.

Transients aren't the only thing that can be wrong with your household electricity. If the voltage is consistently low or high there can be problems. In the US your appliances generally expect the voltage to be 110V, and lesser voltages can cause performance problems.

If the voltage is low something is probably overconsuming. I saw an excellent example of that at a friend's house once, where the lights to their barn were getting progressively dimmer. The power line from the house had been a DIY installation, definitely not in accordance with codes and standards. I told my friend that he probably had a short that was big enough to bleed juice like a fiend but not big enough to trip the breaker. Ah, he remembered a particularly ugly splice in the buried wire and he went to dig it up. A couple of scoops later steam was coming from the ground. He shut it off, respliced it with a better connection and better insulation, turned it back on, and suddenly he had brighter lights and lower power bills.

If the voltage is high, that's probably because the other side of neutral is low. This is bad because it tends to overheat sensitive devices like computer chips. Since computer chips are found in almost anything nowadays, voltage control is more important today than ever before.

Minor variations can make a difference too, because the heat increases approximately with the square of the voltage - a 10% increase in voltage can give you a 21% increase in heat to reject, which forces the operating temperatures up. Even light bulbs won't last as long - if they seem to last longer in some parts of the house rather than others, you might have this problem.

What's "the other side of neutral"? That's too much to explain here, but the cure might be as simple as rearranging the way your breakers are arranged in your distribution panel.

Gosh, I'll bet you wish I had a tip jar now, eh?...

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