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View Full Version : Why is static electricity so much worse in the wintertime?


Stereolab
7th January 2004, 11:03 PM
My Playstation 2 controller zapped me good the other day.

At least I have a good way of getting out my stress over this--I pet my cats and then zap them on the nose.

Walter Wayne
7th January 2004, 11:07 PM
If I recall, it is the dry air which results in dry cloth, dry skin etc. A little bit of moisture reduces the amount of spare electrons things pick-up or drop.

Thats the explaination I remember from high-school.

Walt

Stereolab
7th January 2004, 11:29 PM
Interesting--I would have thought moisture would help conduct the electricity.

fishbob
7th January 2004, 11:49 PM
Moisture conducts away the electricity so that the static charge does not build up.

Walter Wayne
7th January 2004, 11:54 PM
Originally posted by Stereolab
Interesting--I would have thought moisture would help conduct the electricity. Well, that would cause static charge to dissipate before you built up a couple of KiloVolts on your hand. (Actually, your physics sounds better the physics in my first post, so I'll go with the second explaination) I'd google, but it is bed time.

Thanks Stereolab.

Walt

Charlie in Dayton
8th January 2004, 12:41 AM
The following is entirely conjecture on my part...somewhat educated conjecture, to be sure, but conjecture nonetheless...

It's not that it's worse, it's just that you get zapped more often. Dry conditions exacerbate static zaps. In the winter, you're in the house and the furnace is running a lot, and that air is really really dry, and the conditions promoting static zaps are more prevalent.

Summertime? if your house is not air conditioned, the relative humidity matches the outside air, which is usually (unless you live in a desert environment) high enough to help static charges drain away. If it is air conditioned, the humidity is usually governed to a limit that is still above the zap-promoting limits.

Wanna stop this? Get a cheap plastic dishpan, pour a gallon of water in it, and leave it close to the heater duct so the air circulates around it. You'll be amazed -- you'll be pouring a gallon of water every other day into that pan, but the zap rate will be down, and you'll feel better as your breathing passages won't be all dried out. Or get a cheap kid's room vaporizer, fill it up without putting any medication in it, and let 'er rip...the idea is to get some water into the air. I've got an electric atomizer designed to do this (Grandpa found it at a garage sale a number of years back), and it dumps at least a half galllon of water into the air a day in my place...I run mine next to the heat vent in a room where a fan runs continuously to keep air circulating. The window box fan costs something like 2 cents a day to run, and it helps keep my heating bill down.

Cheap? Me? Hell yes...

Scoobmaster
8th January 2004, 05:05 AM
On a serious note - try to make sure to ground yourself by touching the metal body of your vehicle before refueling. This may sound like a silly moot point, but although a rare occurance - static discharge ignited gas station fires DO happen. I notice some BIG TIME discharges when I get out of my car sometims in the cold months!

Crossbow
8th January 2004, 05:58 AM
Originally posted by Stereolab
My Playstation 2 controller zapped me good the other day.

At least I have a good way of getting out my stress over this--I pet my cats and then zap them on the nose.

Because cold air cannot hold as much moisture as warm air can there can be much more charge of the charge separation which results in the build up of static electricity. In other words, dry air is a much better electrical insulator than is humid air.

To minimize the static electricity in a closed area (like a house) run a humidifier, spray the carpet with a fine mist of water, or walk around barefoot.

PygmyPlaidGiraffe
8th January 2004, 09:42 AM
Originally posted by Scoobmaster
On a serious note - try to make sure to ground yourself by touching the metal body of your vehicle before refueling. This may sound like a silly moot point, but although a rare occurance - static discharge ignited gas station fires DO happen. I notice some BIG TIME discharges when I get out of my car sometims in the cold months!

how rare an occurance? so rare that I have never heard of this. More or less rare an occurance than cell phones igniting gas fumes?

Static (http://www.snopes.com/autos/hazards/static.asp) electricity occurances of igniting fumes

Compare cellphones (http://www.snopes.com/autos/hazards/gasvapor.asp) and occurance of ignition of fumes

Scoobmaster
8th January 2004, 10:24 AM
Originally posted by PygmyPlaidGiraffe


how rare an occurance? so rare that I have never heard of this. More or less rare an occurance than cell phones igniting gas fumes?

Static (http://www.snopes.com/autos/hazards/static.asp) electricity occurances of igniting fumes

Compare cellphones (http://www.snopes.com/autos/hazards/gasvapor.asp) and occurance of ignition of fumes


Here is a link with plenty of information (http://www.esdjournal.com/static/refuelfr.htm)

Source:

The ESD Journal (http://www.esdjournal.com/index.htm)

Ove
12th January 2004, 11:50 PM
On a serious note - try to make sure to ground yourself by touching the metal body of your vehicle before refueling. This may sound like a silly moot point, but although a rare occurance - static discharge ignited gas station fires DO happen. I notice some BIG TIME discharges when I get out of my car sometims in the cold months!

You get the discharges because your (synthetic)clothes/you get charged when you rub against the (synthetic)seats.

If you want to avoid those discharges the solution is simple. Get a re-fillable spray bottle, fill it with a solution of 90% water and 10% softener (the stuff you pour into your wash machine to "soften" the clothes). Spray your car-seats with this solution,not dripping wet just make them humid. Repeat this once or twice a year and hey presto.

It works.;)

RussDill
13th January 2004, 12:14 AM
Course, where I live, its the exact opposite. In the Summer, we suck all the moisture out of the air in our homes with air conditioning. The low humidity outside combined with AC makes for huge static opportunities. Whereas in the winter, many homes just run their heat pump in reverse, so the temperature inside is cooler than it was inside during summer months, and mosture is not removed for the air, allowing for higher humidity, and less static.

ceptimus
13th January 2004, 06:37 AM
Best way to get out of a car without any risk of static zaps, is to hold onto some metalwork, say the top of the door, as you climb out. The metal can be painted, and this technique still works.

This really works. I suppose there may be a spark between the sole of your shoe and the ground as you step out, but you never feel anything.

HopkinsMedStudent
13th January 2004, 12:00 PM
Wait a minute. If you want to ground yourself at the gas station, wouldnt touching the outside of the pump work better than touching the car?

Cars are not grounded well because they have rubber tires insulating them from ground contact. Thats why its always better in a lightning storm to be inside your car than just standing around outside.

The metal on the outside of the gas pump runs straight into the ground, i think.

jj
13th January 2004, 12:20 PM
Originally posted by Stereolab
Interesting--I would have thought moisture would help conduct the electricity.

Precisely. When there's no moisture in the air, the charge builds up instead of being conducted away, until you get near to something that is at a different potential, and then ZAP.

In humid conditions the charge does not build up, rather it bleeds off roughly as rapidly as it is created.

The ways that triboelectricity is created is legion, flowing air, flowing water, surface moving across surface ... Things like nylon rugs, fur, etc, excel at being generators. In fact, using the right materials in a dry climate you can build up literally millions of volts of charge with a simple machine.

FORtunately, you can't build up a whole lot of charge, just a whole lot of volts (low capacitance) without some work.

ceptimus
13th January 2004, 03:25 PM
I think it is the car that is charged, not only the person. When you get the shock, you are discharging all the static electricity from the whole car, through your body.

I found the 'hold onto the door technique' only after geting injured!

I used to park the car, jump out, then when I went to close the door, I used to get a (big) static shock.

So I started pushing the door shut using the window glass (glass being a good insulator). However, I still had to lock the car (no remote locking in those days). I used to hold the plastic part of the key and lock the car door, and creep away, mission accomplished, and no shock!

Then one day, a huge spark jumped across to my knuckle, as I was turning the key. I saw it and heard it, as well as feeling it! I yelped and pulled my hand away quickly, but the car key was turned in the lock, and so trapped. The other keys on the key ring, one of them a freshly cut 'chubb' type ripped a large slice out of the palm of my hand. :(

After that, I removed the other keys from the car key ring, but I also discovered the 'holding the door while getting out' trick.

In recent years, these car shocks don't seem to happen to me, even if I don't hold the door in 'static' weather. Maybe the car I drove then had different tyre construction? Something perhaps about the car that resulted in it building up a big static charge, which did not quickly leak away.

jj
13th January 2004, 03:53 PM
Originally posted by ceptimus
I think it is the car that is charged, not only the person. When you get the shock, you are discharging all the static electricity from the whole car, through your body.


Well, it's all relative. By gaining or losing surface electrons, you acquire a different potential than the car, it doesn't matter which of you does which.

A car, if it's not at ground, is larger, and therefore has more capacitance, so it will deliver a larger charge for a given voltage.

For kicks, some day, figure out the results of moving one coloumb of charge from the earth to the moon. Assume for that discussion that both earth and moon are conductive, and that the space in between is not. Figure out what kind of energy that would take.

The point? Electrostatic fields are strong.

Soapy Sam
13th January 2004, 03:57 PM
Colorado in winter. Rental cars with nylon snow tyres. A lethal combination. First time I saw a spark leap from the car to my finger on a gas station forecourt , I nearly had a heart attack. Never did blow anywhere up though.
Contrast winter in Scotland. (Or summer for that matter) , where relative humidity hovers at a perpetual 100% in and outdoors.
Ok, so the wallpaper is peeling, but at least I don't get zapped.

ceptimus
13th January 2004, 04:27 PM
Originally posted by jj
Well, it's all relative. By gaining or losing surface electrons, you acquire a different potential than the car, it doesn't matter which of you does which.jj, I figured when I got out of the car, I earthed myself (thin soled leather shoes), but you don't feel that, as the spark jumps to the shoe, and the current is spread over your whole foot.

Then, when I touch the car, I earthed the car down through my body. Again you feel nothing at your feet, but where the spark enters your finger, you DO feel it.

I think the holding onto the door while getting out works for the same reason - the whole car is earthed through a spark leaping from the sole of your shoe to the ground, but you don't feel it. I suppose the scientific test for this would be to climb out barefoot, while holding the door.

But like I said, my current car (no pun intended) doesn't seem to build up any static. Maybe the tyres have something slightly conductive in them to leak away the static nowadays?

epepke
13th January 2004, 04:34 PM
Originally posted by ceptimus
Then, when I touch the car, I earthed the car down through my body. Again you feel nothing at your feet, but where the spark enters your finger, you DO feel it.

Unless you get a kick out of being zapped, try holding a key and touching the car with the key.

I even get zapped in Florida in the winter. Florida, most of the year, is only slightly less humid than the bottom of a swimming pool. I look at the humidity limitations on electronic components and laugh my head off.

jj
13th January 2004, 04:57 PM
Originally posted by ceptimus
jj, I figured when I got out of the car, I earthed myself (thin soled leather shoes), but you don't feel that, as the spark jumps to the shoe, and the current is spread over your whole foot.


Possible, but not necessary.


Then, when I touch the car, I earthed the car down through my body. Again you feel nothing at your feet, but where the spark enters your finger, you DO feel it.


Again, possible but not necessary.


I think the holding onto the door while getting out works for the same reason - the whole car is earthed through a spark leaping from the sole of your shoe to the ground, but you don't feel it. I suppose the scientific test for this would be to climb out barefoot, while holding the door.


Again, possible but not necessary.


But like I said, my current car (no pun intended) doesn't seem to build up any static. Maybe the tyres have something slightly conductive in them to leak away the static nowadays?
It's also possible that both you and the car are still pretty isolated, but the material in the car seats doesn't generate static at the same rate as the old material did.

The "snap" could just as well be you and the car, both still isolated, but the potential coming about due to you rubbing against the upholstery while getting out. I used to have a car like that. Yeow.

If you hold the metal part of the door while getting out, you'll drain it slowly and silently.

JJ

tamiO
11th February 2004, 10:37 AM
bump :)