Static%20Electricity%20(9-28-2K)
 

Question:

Mike, most people get electrostatically charged when they are in an area of low humidity  especially when they wear woolen or polyester clothing. My questions are:

1. Why do some people get overly charged while others do not?

2. I came across a friend who was so charged that if he touched anything he would get a severe electric shock. I asked him to drink more water and his condition decreased! What is the scientific reason for this?

3. Oftentimes disturbed or excited or tense people are prone to be more charged. Why?

4. I met a person who got charged within minutes and if somebody touched him, they got a severe electric shock. I found that if I continuously hold him he could not get charged. However, as soon as I left him isolated, he gets so charged that one could see arcing, even from his ear! What is the reason for this person to have such physiological behavior?

5. I know of an electrical contractor who was having such a problem for the past ten years. The last time he came to my office, he shook the hand of a fellow worker who was thrown 10 feet away by the electric shock. I asked him to change his clothing material and drink more water. I have not spoken to him since, so I do not have the results.

6. My son gets charged when he is inside the car with the hot air on. I used to get a shock when I was leaving my apartment in Schenectady, NY when I was in GE training. Most of the people get a visual electrostatic discharge with a mild hissing sound when they take off their clothes, especially woolen or polyester.

From: "Soorya B. Shrestha" <snehesh@wlink.com.np>

Mike Holt's Comments:

1. I have no idea why, but I have gotten shocked on a trampoline when it has been exposed to the sun.

2. My wife gets very electrically charged (polyester clothing sticks to her body) during part of her menstrual cycle.

3. I have heard rumors that some factors in the 1950's actually reduced production of sensitive electronic equipment because the women on the assembly line became concurrent with their menstrual cycles!

Note: I did speak to some on this topic and the comment was that women's skin dries out during part of the menstrual cycle and the rubbing of the skin with the polyester clothes created the triboelectric effect. Made sense to me.

Also for more information, see IEEE Standard 142 “Green Book” Chapter 3.

Mike@mikeholt.com

Response No. 1:

The charge came from static electricity generated by friction between material (cloth, floor, shoes and floor) especially in dry locations. In addition, the human body is filled with chemical fluids; the mix of them in most of the cases is an acid (pH over 7). When the body is acid we can conduct electricity very well and we cannot keep much electric charge. But if we are below 7, our body is acting like an insulator keeping a lot of charge. When you drink water or other acid fluids you are adding salts to the body increasing the pH (makes the body more acid).

From:  Delgado, Eric A.

Response No. 2:

Am I correct in assuming that this static problem with filling gasoline containers applies only to metal ones? Thanks.

From: Herring, John W.

Response No. 3:

In reference to the memo you sent about fire during gas dispensing (memo attached to this newsletter below), many companies, such as Grainger's and McMaster-Carr, sell decanter- grounding cables with clamps. The grounding cables are inexpensive and easy to install. They should be installed anywhere that flammables routinely are decanted from drums and other storage containers. The memo that was quoted in your newsletter mentioned always placing the container on the ground but, while that is certainly prudent, that may not be adequate. The cables, incidentally, are usually colored bright safety orange. Most electrical folks would probably relate better to the cables if they were green but cables are a safety device and most folks recognize the bright orange as a safety device color.

The memo mentions that "a charge can accumulate on the surface of the ungrounded container, thus creating the potential for an electrostatic discharge between the mouth of the container and the dispenser's nozzle."  But, the next paragraph says, "a charge can accumulate on your body, thus creating the potential for an electrostatic discharge between your body and the dispenser’s nozzle."

Both statements are correct but that could lead some readers to believe that the charge on the receiving container is created only by the charge that accumulates on the person's body. Fuel moving through the piping and the nozzle create the charge on the receiving container. Here is why this is an important distinction to make. If a person were to approach a container that has just been filled, he may intentionally discharge himself before going near the container, thinking that he is safe because he has discharged himself. However, a charge may exist at the container because of the fuel moving through the pipe and nozzle so a potential may exist between the decanter and the container.

From: Wells, George

MEMO SENT OUT PREVIOUSLY

I work for an oil company. There have been reported cases where it is believed at our gas stations that static electricity caused a fire during dispensing gasoline. Below is a statement from my company:

We in Corporate Environment & Safety want you to be aware of certain static electricity fire and explosion hazards that may exist during the fueling operation. Recently, there have been several documented cases where the discharge of built-up static electricity has apparently ignited flash fires, resulting in personal injury to retail customers as well as property damage to retail locations. Actions that may contribute to such situations include filling portable gasoline containers, which are not resting on the ground, as well as re-entering your vehicle while fueling is underway. In the case of filling portable containers, the electrostatic charge is generated by the flow of gasoline through the dispenser's hose. A charge can accumulate on the surface of the ungrounded container, thus creating the potential for an electrostatic discharge between the mouth of the container and the dispenser's nozzle. A flash fire can result from this discharge if sufficient flammable vapors are present at the mouth of the container. Therefore, portable containers should always be placed on the ground during filling, and the nozzle should be kept in contact with the container.

In the case of re-entering a vehicle while fueling is underway, the electrostatic charge is generated by the action of dissimilar fabrics (i.e., clothing and upholstery) rubbing across each other as you enter or exit the vehicle. A charge can accumulate on your body, thus creating the potential for an electrostatic discharge between your body and the dispenser's nozzle. As in the case above, a flash fire can result from this discharge if sufficient flammable vapors are present.  Therefore, we advise you not to re-enter your vehicle while fueling is underway. In addition to the static electricity issue, we would also like to take this opportunity to remind you of the potential danger in using electronic devices near the fueling point. Cellular phones and other electronic devices may have the potential to emit electrical charges, and should therefore be turned off and left in the vehicle during fueling to decrease the possibility of an inadvertent ignition of any flammable vapors that may be present in the fueling area. Thank you for your cooperation.

From:

Response No. 4:

I saw a similar memo about two years ago. It also stated that static electricity can build up on the gas can as it slides around while riding in the back of a truck with a vinyl bed liner. The bed liner  (and the tires of the truck) acts as an insulator and the static will remain on the can till it slowly dissipates. This time may be longer than the time needed to start the fueling process. By moving the can to the concrete pad, the can's bottom outer surface is then grounded and most of the static charge will dissipate. In our chemical lab we have some plastic safety cans similar to the standard gas can except they have a metal ring around the mouth. We then have a grounding strap connected to this ring.

From: Cook, John

Response No. 5:

My two cents: Going along with the "drink more water theory," humidity and dryness of skin alters a "normal" dissipation of charge. The less humid and less bodily conductivity allows the charge to build up until an appropriate path is found.

From: Widener, Doug

Response No. 6:

I would always get shocked in the winter during dry conditions. I found that if I had on Rockport sneakers I would get shocked whenever I touched my car. If I were wearing leather boots, I would never get shocked. The conditions for more electrostatic charge are probably everything from moist feet, material of socks, shoes, amount of electrolyte in the body, etc. A solution that I found that always works to reduce electrostatic shocks is to get 25 feet of stranded #6 bare copper wire, wrap it around your waist three times and let the rest follow behind you. Guaranteed to work.

From: Feindt, Bill

Response No. 7:

Regarding your newsletter relating the electrical shock and close call of Michael White of Corbins Service Electric, this reminds me of the slogan Florida Power & Light drilled into me as a co-op student: "ground it out or work it hot." I never hear this from electricians, but there is no reason why. A jumper with clamps at both ends would serve well as the ultimate tester that the circuit is indeed dead.

From: Rebane, Henn

Response No. 8:

These charged-prone people could have a high sodium level. Salt, in conjunction with our fleshiness relates to the conductor properties, which relate to the amperage felt at discharge.

From: ComL64

Response No. 9:

After reading your post I will recommend providing your personnel with discharge straps, "some of them are used on the shows and discharge very well the person who used them." They are supplied for electronics where static is a problem. If you have trouble finding a supplier, check the ads in test and measurement magazines or contact me by e-mail.

From: SAVADI

Response No. 10:

1. Why do some people get overly charged while others do not?

A function of body/skin moisture content, which is related to the serum sodium level (amount of sodium and/or salt within the blood).

2. I came across a friend who was so charged that if he touched anything he would get a severe electric shock. I asked him to drink more water and his condition decreased! What is the scientific reason for this?

Increase of water altered the serum sodium level (see above), thus changing the ionization/static susceptibility level of that person.

3. Oftentimes disturbed or excited or tense people are prone to be more charged. Why?

Again, body chemistry is the key to understanding this phenomenon. Some people undergo a drastic blood ion level change when excited, etc. Doctors have spent years studying this and similar stuff.  It helps them in the treatment of certain heart diseases and strokes.

4. I met a person who got charged within minutes and if somebody touched him, they got a severe electric shock. I found that if I continuously hold him he could not get charged. However, as soon as I left him isolated, he gets so charged that one could see arcing even from his ear!  What is the reason for this person to have such physiological behavior?

That person is one of those folks whose outer skin layers are able to hold a very high static charge. The fact that it disappears when you firmly held onto him simply points out that you were extremely low in static potential, and you drained his charge away.

5. I know of an electrical contractor who was having such a problem for the past ten years. The last time he came to my office, he shook the hand of a fellow worker who was thrown 10 feet away by the electric shock. I asked him to change his clothing material and drink more water. I have not spoken to him since, so I do not have the results.

These stories are among the anecdotal occurrences that yellow rags like the National Enquirer love to exploit. There are scientific/medical explanations for this, although the condition is rare.  Your suggestions would have undoubtedly reduced some of the charge. These same people are the ones who cannot wear a watch and have it keep proper time.

6. My son gets charged when he is inside the car with the hot air on. I used to get a shock when I was leaving my apartment in Schenectady, NY when I was in GE training. Most of the people get a visual electrostatic discharge with a mild hissing sound when they take off their clothes, especially woolen or polyester.

Many people get charged if they trail their hand outside a car window on a cold, dry day.

From: Soifer, Allan

Response No. 11:

Most of the people get electrostatically charged when they are inside low humidity rooms and they would get more charged if they were wearing triboelectrically different material. My questions are:

a) Why some people get overly charged while others do not.

This is probably from minute differences in the leakage paths for currents. The amount of charge involved is very small, and voltages are very high. Thus, it's easy for all of the accumulated charge to leak off of someone through some impossible-to-detect path made of, say, dirt, salt, and moisture.

b) I came across one of my friends who was so charged that if he touched anything he used to get an electric shock. I asked him to drink more water and he became all right. My interpretation is that if somebody had less water quantity, then he can be charged. But what is the scientific reason?

I think that when someone drinks a good deal of water he is apt to sweat a bit more. The salt- laden moisture would have provided a leakage path to the earth, so he wasn't able to retain the charge on his body.

c) Generally disturbed or excited or tense people are prone to be charged. Why?

I don't think this is true.

d) Recently in my city there was a person who happened to be charged so fast that within minutes if somebody touched him he would get an electric shock. I personally went to meet the person to get an electric shock and found that if I continuously hold him he could not get charged. But as soon as I leave him isolated he gets so much charge that one can see arcing even from his ear! What is the reason for this person to have such physiological behavior? Our Science Academy people have a version of the case being that of neurology. I think they are joking. And mind it, I gave him a lot of water and it decreased! What is the reason for such decrease?

Once again, it very likely has to do with the paths available for leakage currents to flow. Skin moisture, clothing, and the particular environment that someone is in will all affect the body’s surface conductivity. It doesn't take much surface conductivity to leak off all accumulated charge to ground. There is also a possibility that the person is wearing some sort of nylon underwear.  This is notorious for causing static charge buildup on one's extremities.

e) Again, I have an electrical contractor who was having such a problem for the past ten years.  The last time when he came to my office, he shook hands with another fellow who was thrown about 10 feet away by the shock. I asked him to change his dressing behavior. It decreased. I have asked him to drink more water. I haven’t spoken to him since, so I do not have the results. Ten feet?

f) My other question is why people get electrostatically charged when they are in low humidity areas. My son gets charged when he is inside the car with hot air on. I used to get a shock when I was leaving my apartment in Schenectady, NY when I was in GE training. Most of the people get a visual electrostatic discharge with a mild hissing sound when they take off their clothes, especially woolen or polyester.

My socks tend to stick together when I take them out of the dryer. Dry air tends to eliminate the moisture that aids surface conductivity. The same amount of charge is transferred in humid conditions as in dry conditions, but it cannot be accumulated if leakage paths carry off charge as fast as it can be generated.

From: Mark Kinsler <kinsler@adenine.frognet.net>

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