When it comes to elevators, our biggest fear is that the cable will snap and the elevator will fall to the bottom of the shaft. People debate whether there is anything you can do to save yourself---jumping just before you hit is the most popular suggestion. A few years ago, Mythbusters did a test, and the result was not pretty. Jumping doesn't help.

Elevator engineers could have told you that. If our legs were powerful enough to jump hard enough to counter the speed of the fall, they would also be powerful enough to absorb the impact. Heck, if our legs were that strong, we'd all be able to jump very high. Apartment buildings up to about five stories wouldn't need stairs---people would just jump up onto their balconies from outside.

On the other hand, I've long suspected that such elevator falls are extremely rare. Although hoists of various kinds go far back in history, we didn't start putting passenger elevators in buildings until after Elisha Otis invented a mechanism to prevent elevators from falling. Modern elevators are defined by their inability to fall. My guess was that fatal falls happened less than once a year, at least in this country.

According to a fascinating article about elevators by Nick Paumgarten in the New Yorker, I'm way off, but in a good way: For a long time, there was only one known free-fall incident in a modern elevator. It happened in 1945. And it happend when a B-25 bomber struck the Empire State Building in the fog. The impact cut all the cables on two elevators, which fell all the way to the bottom. There was only one person in the elevators at the time, an elevator operator. She was hurt bad, but she survived.

(The terrorist attack on the World Trade Center---which also involved airplanes hitting buildings---killed a bunch of people in elevators, a few of whom probably died from falls down the shaft.)

If you've ever seen the top of an elevator, you know there are a bunch of cables holding it up. Every single one of those cables can hold the entire weight of the fully-loaded elevator. Many elevators also have brakes that lock the elevator to its rails, so even a loss of all the cables wouldn't make it fall. Finally, there's a hydraulic buffer at the bottom of the shaft to cushion the impact.

For all practical purposes, nobody ever dies in an elevator fall. In fact, of the 20 or 30 elevator-related deaths each year, most of them are maintenance accidents---technicians leaning too far into the shaft or getting caught between moving parts.

However, if you still want your elevator rides to have some thrills, there are always the hazards of elevator doors to worry your mind, such as people stepping blindly through doors that open into empty shafts or being strangled by scarves caught in the doors. If you want something really scary to spice up your elevator rides, sometimes the door-open safety mechanism fails and an elevator suddenly moves while people are getting in or out. The results are often gruesome, and sometimes end with the elevator passengers riding up a few floors with a severed head.

Libby asks:

How do light bulbs unscrew themselves? This can't be only be happening to me. My lamps are really old and rickety for the most part but I don't think that's the reason that I have to retighten the bulbs every once in while. Sometimes I think the bulb is out and discover it's just not twisted in far enough. And today I changed a bulb that did burn out but it was only one twist away from unscrewing itself and leaping to the floor.

Are my lightbulbs just suicidal or is there a scientific explanation for this do you think?

This is one of those questions that stuck in my head...let me try some guesswork.

Light bulbs are held in place by friction between the threads of the bulb base and the threads of the socket. The friction forces tend to prevent movement of the bulb, but they don't actively force the bulb into the fully-seated position (where the center electrical contacts are touching, allowing the bulb to light). So if some outside force unscrews the bulb out of the seated position for any reason, it stays there unless another outside force pushes it back.

Assume that some random force occasionally nudges the bulb. This nudge will either screw the bulb further into the socket or unscrew it out of the socket. If the bulb is already fully-seated in the socket, it can't screw in any further. (Actually, it can move a little bit by deforming the socket and base a bit, but that takes more force than simply screwing or unscrewing.) On the other hand, the bulb can always move in the unscrewing direction. There's nothing to stop it until it falls out.

If the random forces are not perfectly balanced, they will tend to nudge the bulb more in one direction than the other. If they tend to unscrew it, over time they will eventually loosen it enough to break the electrical contact and the bulb will go out. You'll notice that and discover the loose bulb. But if the random forces tend to screw the bulb in, it will just stay snug in the socket and you will ignore it.

So what are these mysterious random forces that move the bulb?

Two possibilities come to mind. The first is thermal cycling. When the lamp turns on, the parts of the bulb base and socket heat up, causing them to expand. However, not all parts heat at the same rate. In addition, the parts are made from different materials which have different expansion charactistics. Thus the parts change size, but not in perfect synchronization, which creates internal stresses that push on the bulb, loosening it or tightening it.

(This used to happen with old socketed computer chips such as the CPU and RAM. Over hundreds of turn-on/turn-off cycles they would expand and contract and slowly walk themselves out of the socket until the computer died. I remember some old computer equipment where the first line of problem diagnosis was to pull all the cards and press down firmly on every single chip. It often solved the problem. Most modern computers use complex sockets designed to prevent things from creeping loose—this is why CPU modules and memory cards usually have a retainer that snaps into place.)

Once a bulb unscrews itself this way, it goes out, and therefore thermal cycling stops, which means that thermal cycling can't turn a bulb back on again. On the other hand, it can't unscrew a bulb beyond the point where it stops working, so this doesn't explain how Libby found a bulb that had nearly fallen out. Some other forces must be at work.

All I can think of is random vibrations from things like people walking around, passing vehicles, and circulating air currents. Again, if these vibrations are not perfectly balanced—and they never are—then they will tend to nudge the bulb more in one direction than another. If they're pushing in the unscrewing direction, they will nudge the bulb away from the electrical contacts and eventually out of the socket.

That's about all I can think of to explain the self-unscrewing-bulb phenomenom.

Unless you have cats. They do stuff like this all the time 'cause they think you'll never suspect them.

The New York Times has a Flash illustration of Cory Lidle's plane crash that is just a terrific example of how to use computerized media to explain a news story. Check it out.

Well, I thought my electrical problems were over.

About five minutes ago, however, the lights went out. Looking out the windows, I can see that the lights are out in several neighboring blocks as well. I can still see skyglow, and some lights further away, so it's not the whole city.

(4 minutes to shutdown.)

After the first couple of minutes, the power came on for about 15 seconds and then went off again. That can't be a good sign. It probably means that some sort of backup plan has also failed.

(2 minutes to shutdown.)

Still dark.

Until civilization returns, this is Windypundit, signing off...

Update: Power came back on about 10:20 local time.

The best part is that the UPS for the Tivo didn't give out—although it was sounding the alarm for the last few minutes before power returned—so we got all of the Daily Show.

What? Doesn't everyone have their DVR and cable box on a UPS?

(Links to Chapter 1, Chapter 2, and Chapter 3.)

When I first called ComEd's customer service center to complain about the electricity in my house, I wasn't even sure that 135 volts AC was out of the accepted range for electric service. While several consumer web sites have information about electricity costs and rules for disconnection, the web has surprisingly little about electrical service quality and voltage standards.

(Thanks to Firefly Digital Media for a comment clarifying that "135V is indeed WAY too high, and it's not a matter of ComEd WANTING to fix it. It is a violation of standards that can threaten public safety.")

I guess my easy-going telephone personality and my hesitancy over whether this was even a problem caused ComEd to not take me very seriously. As of Tuesday morning, a week and a half since I first brought the problem to ComEd's attention, the household electricity was coming in at 137 Volts AC.

It was time to use my nuclear option: I let my wife handle it.

You see, I don't like putting pressure on customer service people. I hate it when people put me on the spot for things, so I'm reluctant to do it to other people.

My wife, on the other hand, does customer service for a living. She's worked in call centers, managed call centers, and set up call centers. Providing good customer service is a very big part of her job. So when she calls other customer service centers and they don't solve her problem, she shows no mercy. Without making threats or being unfriendly, she makes it absolutely clear that they're not going to get rid of her without doing exactly what she wants.

One hour after her call to ComEd, I spotted this guy out the window:

After checking our power line directly, he backed the truck up to the transformer drum that serves my building and checked something there. Then he proceeded up along the distribution lines, checking one transformer on each high-voltage line that serves each block, until he got to the last pole where the lines go underground. (Yes, I followed him.) Then he drove off to do something else.

About an hour and a half later I'm sitting at my computer when I hear the UPS click and the lights get dim. I notice these brief brownouts a couple of times a month. Except this one is lasting longer than they usually do, and although the UPS clicked like it always does, it isn't buzzing with 60Hz hum from supplying battery power to the computer...

Oh.

I pull out the DMM and check an outlet. 122 volts.

So when I called ComEd, nothing much happened for a week and a half; but when my wife calls ComEd at 9am, they fix the problem by noon.

Sigh.

As an aside, here's something that makes me glad I don't have to troubleshoot electric power distribution systems:

I've been measuring the household voltage by sticking the probes on my multimeter into the two slots in an ordinary outlet on the wall. Here's a picture of the probes:

As you can see, they're about 5 inches long and have maybe 1/8 inch of insulation. That's plenty for measuring the household 120 volts (or so). In fact, the meter and probes are rated for 1000 volts.

Now take a look at the probes the ComEd technician was using to check the high-voltage distribution lines:

Damn, that must be a lot of voltage.

I did some more exploration of the local electrical power situation I outlined in my previous two postings. (Part 1 and Part 2.)

I drove to another block fed by a different phase of the same three-phase distribution lines that feed my building. After a couple of times around the block, I spotted an apartment building with an outdoor outlet, so I parked and walked up to test it. Unlike the night before, this one had power: at almost exactly 120 volts too. So not all phases were affected.

I drove around the remaining block on the third phase until I spotted a guy watering his front lawn. I wasn't looking forward to trying to explain my purpose—this is serious geek territory—but I got out of the car and walked up.

"Excuse me. I...I live in the next block, and we're having trouble with our electricity. Are you having any trouble with yours?" If he was, or even suspected he was, I'd have an easier time getting his cooperation.

"No."

"Well, I'm trying to figure out how far it spread...how many people are affected." I pulled out my digital multimeter; I had already spotted an outdoor outlet. "Do you have an outlet where I could check the voltage?"

"Go right ahead," he said waving to the outlet. "We usually get 127 volts."

Thank you, brother.

"Well," I responded, "I've been getting 137."

I walked up and plugged in.

"122 volts," I read off. "So you're fine."

He suggested it was a problemn with the transformer, and I explained why I didn't think so. We spent a few more minutes discussing it, then I thanked him and left.

So, it's only my block. That means it will be harder to rally a crowd to pester ComEd to fix this.

On the other hand, maybe they'll fix it this weekend, when the down time won't bother people as much. We'll see.

As I mentioned in my last entry, we're having a few electrical problems at our house. ComEd is supposed to supply voltage at 120VAC (Volts Alternating Current). That's just a nominal value, it can vary a bit. ANSI standards supposedly permit 5% variation, from 114 volts to 126 volts. ComEd's rule book says they may have 5.8% variation, from 113 volts to 127 volts. This past week, I'm measuring anything from 133 volts to 139 volts. The speakers attached to my wife's PC blew out last week, and one of the 300W quartz-halogen lamps burnt out a few days ago.

I've called ComEd twice, and they haven't fixed it. On Monday a truck came by and they took a look at the transformer drum mounted on the pole in the alley behind our house. (Here's a few pictures of a transformer drum at HowStuffWorks.) However, since then nothing has happened. I've been compulsively checking the line voltage ever since with my DMM (Digital MultiMeter). It was 137 volts just a few minutes ago.

There must be tens of thousands of transformer drums in the city of Chicago alone, so ComEd must be replacing them all the time. I've been wondering why they haven't replaced ours yet. The rule book says that voltage shall not exceed 127 volts for more than one minute, but it's been more than that for a whole week.

I think I've now got it figured out. I was restless tonight (this morning) and couldn't get to sleep, so I took a walk. I took my DMM with me. I was looking for outdoor outlets. I wanted one right on the side of the building, so I could get to it without entering anybody's backyard.

Down at the end of the block is a small apartment building that has an outdoor outlet in their parking lot. I flipped on the DMM, turned on the backlight for the display, flipped up the cap on the outlet, and stuck in the probes. 138 volts AC. Bingo.

All the buildings on that end of the block are fed by a different drum transformer than our building. That means the problem is not in the transformers in our alley. The problem is further upstream in the distribution grid, at some substation nearby. It's a bigger problem that's taking longer to fix.

The drum transformers tap into three-phase lines running high up on the utility poles. Both transformers I tested are attached to the same phase. I walked down the street in the other direction to where the buildings were on a different phase and found an outside outlet I could get to, but it wasn't turned on. I wonder if all the phases are affected?

Anyway, now I have a plan.

This high voltage is against the rules for electrical service in Illinois. It damages delicate equipment, strains motors, and causes light bulbs to burn out faster. It also raises peoples' electric bills.

Maybe tomorrow I'll follow the power lines a little further and find a few people who will let me check their voltage, especially in some of the businesses on Milwaukee Avenue. If enough of us bitch to ComEd about the problem, maybe they'll hurry up and fix it.

Here's a question that's turning out to be harder to answer than I would have thought: What's the acceptable voltage range for your house?

A few days ago the lights flickered and the speakers on one of my computers started making funny noises. Turns out they're fried. That computer system wasn't on a UPS, so I went out and bought an APC Back-UPS 800 for it.

When I plugged it in, it wouldn't go on-line. It would provide power from the internal battery, but it refused to pass through the power from the wall outlet. Reading through the troubleshooting materials, I decided either the UPS was busted or there was something wrong with the household power. This latter possibility made some sense, as my other UPS had started switching to battery several times an hour.

I don't know much about electricity, and I have no real idea how to evaluate electrical noise, so I checked the only thing I know how to check: Voltage. Household power is supposed to be at 120 volts and when I've checked the wiring on outlets, I've usually seen something close to that.

When I check now, however, I get a reading of 135 volts, give or take a volt. I figured out how to hook two of the UPS boxes up to my computer, and they are reporting about 137 volts.

That's high, but is it too high?

I assume ComEd has a commitment to provide electrical power of a certain quality. Somewhere there's a spec that says what voltage range is acceptable. For example, if voltage is allowed to vary 5%, then ComEd would have to deliver household power at somewhere between 114 and 126 VAC.

I've tried to find out what this is, to see if I would be justified in calling and complaining, but I can't find it anywhere. The ComEd website has all kinds of information about bill payment, energy prices, and safety, but nothing about the specifications of their product. They invite me to report blackouts or downed wires, but they don't tell me what to do if the voltage gets out of spec.

The local Citizen's Utility Board website is also useless. Lots of stuff about regulation and pricing, but nothing about the quality of ComEd's product.

Well, I've had equipment damage, my UPS rejects line power, and the voltage is measurably high, so I decided to call the blackout report number on Friday and complain. I called again on Monday. On Monday evening a couple of trucks were parked next to the pole with our transformer on it. They were there at least half an hour. However, nothing has changed: I still measure 135 volts.

Also, one of the quartz-halogen lights just burnt out. Was it about due, or was it hurried to its demise by the high voltage?

So, am I getting poor products and customer service from a big corporation that has a monopoly? Or am I the crazy guy who keeps calling to complain about the voltage? And even if I'm crazy, what do I do about the UPS that won't work in my house?

Update: In something called The Information and Requirements For The Supply of Electric Service provided by Exelon (ComEd's parent company) section 1.051(a) says:

On the Company's 120V standard, the range of acceptable voltage is 127 volts maximum and 113 volts minimum.

So I'm right. The power supplied to my house doesn't meet spec.

Now the trick is getting them to fix it...