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I am an engineer and in the technical department for an ESD company. We deal with static solutions for high tech industries.
The stuff that you are dealing with in your home and in your car is a lot higher voltages than what is acceptable to the electronics industry, but it works the same way.
We feel discharges of about 3000 volts and as high as 10's of thousands of volts. Everything always charges. Tribocharge is basically the contact and separation of dissimiliar materials. When I pet one of our cats in the drier winter months, I literally feel little shocks everytime and if you do this in total darkness, you can see the little arcs!
The reason we get shocked usually is because we are the ones that charge up to a high voltage and we discharge rapidly or get shocked when we touch a metal door handle or the screw on a light switch plate.
We install static conductive (2.5e4 or 25,000 ohm to 1e06 or 1 Meg Ohm) and static dissipative (1e06 to 1e09 ohm) floors and provide esd footwear. It also works to treat a floor with an anti-stat chemical. If you've got carpet, you can take a spray bottle and put about 9 parts water to about 1 part fabric softener (like downy or cling free). So the cling-free sprays and pads really do work to a point. I go around the house barefoot or in my socks, so that's better than the best ESD shoes on the market. Oh, and I have a pair of Convers SD ESD shoes that I wear on job sites for ESD testing.
The human body is more conductive than it needs to be to dissipate ESD charges, but you can't usually go around without shoes. Besides that, in production and test areas or ESD Sensitive areas, they want to keep the personnel at at least 1 meg ohm from ground. This protects them from high current if they should encounter AC line voltages. Besides that, you don't want to discharge too quickly. It's like a charge going down a slide. The slide can't be too steep or you discharge too much energy too quickly or arc over. If the slide is not steep enough, well the charge has no fun! It sits there and causes an ESD event before the voltages get down to a safe level.
So the shoes you are wearing, the clothes on your body and the floor you are walking on all play a part. When you are walking on a sidewalk, you are probably on a porous concrete slab which has quite a bit of moisture in it and if you had esd shoes, sole grounders, etc. on, you would stay at a low charge. But once you go onto a highly insulative VCT, sealed wood floor, or residential carpet, you have no where to dissipate those charges to.
What's practical in electronics environments is not so much in the residential or commercial environments. I'd like to find a solution for these other markets, but it would have to be affordable and practical enough to justify doing it.
We can install an ESD floor that has about 100,000 ohms from point to point (between two probes placed 3 feet apart or from Resistance to Ground (any point on the floor to electrical ground or earth (ANSI/ESD S6.1 and ANSI/ESD S7.1-2005 per ANSI/ESD S20.20-2007) I also have the equipment and have been providing our end-users with Body Voltage Generation tests that show exactly how much voltage I hold with respect to ground on our ESD installed floor through my ESD footwear. The voltage is typically less than +/- 10 volts.
I'm sorry to bore you folks with this stuff. This is what I'm doing at work when I'm not posting on City-Data. That and answering phone calls.
The basic laws of ESD; you can dissipate the charges on a conductor, but not an insulator. Some insulators and isolated conductors cannot be removed from the ESDA (ESD Sensitive Area). If you discharge a conductor within the vicinity of an isolated conductor, a charge will be induced onto it. With an insulator, it will hold a charge until something interacts with it, thus and ESD event. The only way to deal with these two situations is typically with the use of an ionizer. These things pump a balance of + and - ions into the air and they really work.
For your house, they say plants help. Obiously, as was mentioned, humidity works too. If you could get the humidity up to between 35 to 50 %, it would knock the charge generation from your carpet from 10's of thousands of volts to around 1500 volts. Remember, we can't feel or sense much if anything below about 2500 volts. People vary. Some people are kind of dry compared to others. I'd like to learn more about this myself. Whenever I go into my office, I test my Converse shoes on this combo-tester of ours and this one time I had a really bad cold and I could not pass the test. I was too dry.
Silk and wool are obviously pretty bad. Cotton is good. Wear cotton and be sweaty! Seriously though. When you gas up, touch some metal before you grab the gas pump. If when removing the pump from your car and it ignites, just leave it in your tank. The fumes are what's burning and they probably won't blow up. Look for the shut off. It's when people pull the pump away from their car that the gas stream ignites! I've never seen this happen, but I trained with a guy who's dedicated his career to this study. He's from South Carolina.
Moderator cut: solicitation
Last edited by SunnyKayak; 10-31-2007 at 11:18 PM..
We've got a product on the market called a Versa Stat which plugs into ground and creates a 36" "Ground Field" that dissipates charges around it to protect things like A/V equipment, computers, TV's, office copiers, and who knows what else. We haven't really sold too many of them yet. I have tested this thing with a Van de Graaff generator and you can literally hear the generator stop popping.
Without the device, I can feel the hair on my arm raise as I approach the generator. If I have this thing out in front of me, I feel nothing. As I get closer to the generator, the popping sound or arcing stops.
I tell my wife, "The next time you go a round with me, you're gonna light up like a pinball machine and pay off in Silver Dollars!"
Just saw a news report yesterday about a guy who was filling the gas tank in his car and he set the handle and got back in the car to wait till the nozzle clicked off. When he went back and touched the nozzle, static electricity ignited the vapors and there was a huge fire. It showed the guy running with his clothes on fire. I have seen this before in winters past. It can happen in the summer also but we don't usualy get back in the car in the summer. If you feel you must get back in the vehicle while you are fueling BE SURE TO TOUCH SOME METAL PART OF THE VEHICLE BEFORE YOU TOUCH THE NOZZLE. Preferably an area that is away from the fuel door. Better yet, just stay outside with your hand on the fuel nozzle.
When I was in the Army many years ago I was a crew chief on a helicopter. When it got fueled I grounded the chopper to the ground, the tanker to the ground, and the chopper to the tanker. A three way ground required by Army regulations. We don't ground our passenger vehicles. When you get in and out of your vehicle static electricity can build up and when you touch the nozzle a charge can jump between your hand and the nozzle or metal of the car at the nozzle and cause a spark. It is a positive charge jumping to a negative ground with an air gap between. In the air gap are the fumes. Don't think it can't happen. It has happened many times to people who thought it would never happen to them. It is much better to be cold for a few minutes than to have to suffer from burns that could takes weeks or months to heal. Some gas station attendants are shutting off the pump now when they see someone get back in a vehicle while it is fueling.
Besides that one photo above, no one has mentioned the annoyance of static hair? How do you combat that? Here in Wisconsin, I spray my hair with Static Guard in the winter, but it never lasts very long, and I hate my hair sticking to my face!!
I feel like if I moved to Denver and still had this problem, I'd likely chop my hair! Does anyone else have trouble with this?
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