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Electrostatic discharge on bus?

A

Acceed See

Jan 1, 1970
0
I have discovered several times after I leave the bus seat and grab the
stainless
steel pole, there was a pak sound. Is that a ESD? Are the charges from my
hand
or the pole?
 
O

oðin

Jan 1, 1970
0
I have discovered several times after I leave the bus seat and grab the
stainless
steel pole, there was a pak sound. Is that a ESD? Are the charges from my
hand
or the pole?

I do not give a ****.
 
J

John_H

Jan 1, 1970
0
Acceed said:
I have discovered several times after I leave the bus seat and grab the
stainless
steel pole, there was a pak sound. Is that a ESD? Are the charges from my
hand
or the pole?

From your clothes, via your hand.

To eliminate the effect try grabbing the pole, or any other earthed
(to chassis) part of the bus, while your bum leaves the seat -- which
is the point at which your clothes become charged.

Works for me everytime -- car or bus.
 
D

Don Taylor

Jan 1, 1970
0
Acceed See said:
I have discovered several times after I leave the bus seat and
grab the stainless steel pole, there was a pak sound. Is that a
ESD? Are the charges from my hand or the pole?

Certainly could be static discharge, two different materials,
like fabric and plastic, rubbing against each other can
transfer charge.

If you can still find an old fashioned neon bulb, a tiny little
glass container with two wire electrodes separated by a bit of
neon gas inside, you can hold one lead of the bulb and let the
other get close to the pole. You might shield the bulb from
the light in the bulb, so you can still see it but it won't be
overwhelmed by the lights on the bus, then you might be able
to see a brief flash in the bulb as the sparck jumps from the
pole to the free lead. There are more sensitive detectors but
this might be enough for your testing.
 
P

Pharmanaut

Jan 1, 1970
0
John_H said:
To eliminate the effect try grabbing the pole, or any other earthed
(to chassis) part of the bus, while your bum leaves the seat -- which
is the point at which your clothes become charged.

Works for me everytime -- car or bus.
I thought that in a car it was the air rubbing electron off of the
car, which is insulated from ground by it's tyres, that caused you to be
charged. And that you earth the car to ground as you step out... bloody
painful sometimes!

Pharm..

--
Drop the dex to reply.

"...The people can always be brought to the bidding of the
leaders. That is easy. All you have to do is tell them they are being
attacked, and denounce the pacifists for lack of patriotism, and
exposing the country to greater danger "
-- Herman Goering at the Nuremberg trials

"They that can give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."

- Benjamin Franklin, 1759
 
Investigations into the urban legends of cell phones sparking explosions at
the gas pump have fingered the *real* culprit - static electricity generated
when someone wearing synthetic fabrics *slides* out of the driver's seat
(also fabric covered) and touches the pump handle, usually after the tank
has been filled.

Doesn't happen much with cotton, though. Or to people (like most men) who
don't get back inside the car while they are pumping.

There is no significant "air rubbing" when the vehicle is parked at the
pump.

"No, dear, that dress does NOT make you look fat, but just to be on the safe
side, use the full-service pump."

Maybe the OP should wear cotton or denim on bus rides.

That doesn't work. I know from experience. I would really
like to find a way to degauss myself at will. I get out of
my car and touch my winter coat-wrapped elbow to the car; get
a poke. I still get a huge poke when I remove the
key from the lock.

I also have the problem that walking around in the grocery
store charges me up to the point that I get a surge that
feels like an electric fence when I touch the checkout
counter.

/BAH

Subtract a hundred and four for e-mail.
 
[email protected] wrote in

degaussing won't work, that removes magnetic fields.

Discharging once doesn't work, so I figure there has to be
something else that turns into a charge.
You probably have plastic or rubber soles on your shoes.

If you had leather soles, the charge would probably leak to the floor
through the shoes.

They are leather boots. I don't know what the soles are.
You could probably modify your shoes to provide a high resistance but still
conductive path to ground.

When JMF decided to show off the second to last CPU he worked on,
I had to put a collar thingie around my shoe to prevent an
inadvertant teensy little spark while walking around on the
machine floor. I still don't know exactly what that was. I still
have the shift he had to wear.

/BAH


Subtract a hundred and four for e-mail.
 
T

tadchem

Jan 1, 1970
0
I thought that in a car it was the air rubbing electron off of the
car, which is insulated from ground by it's tyres, that caused you to be
charged. And that you earth the car to ground as you step out... bloody
painful sometimes!

Investigations into the urban legends of cell phones sparking explosions at
the gas pump have fingered the *real* culprit - static electricity generated
when someone wearing synthetic fabrics *slides* out of the driver's seat
(also fabric covered) and touches the pump handle, usually after the tank
has been filled.

Doesn't happen much with cotton, though. Or to people (like most men) who
don't get back inside the car while they are pumping.

There is no significant "air rubbing" when the vehicle is parked at the
pump.

"No, dear, that dress does NOT make you look fat, but just to be on the safe
side, use the full-service pump."

Maybe the OP should wear cotton or denim on bus rides.


Tom Davidson
Richmond, VA
 
B

bz

Jan 1, 1970
0
.....

That doesn't work. I know from experience. I would really
like to find a way to degauss myself at will.

degaussing won't work, that removes magnetic fields.
I get out of
my car and touch my winter coat-wrapped elbow to the car; get
a poke. I still get a huge poke when I remove the
key from the lock.

I also have the problem that walking around in the grocery
store charges me up to the point that I get a surge that
feels like an electric fence when I touch the checkout
counter.


You probably have plastic or rubber soles on your shoes.

If you had leather soles, the charge would probably leak to the floor
through the shoes.

You could probably modify your shoes to provide a high resistance but still
conductive path to ground.



--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

[email protected] remove ch100-5 to avoid spam trap
 
B

bz

Jan 1, 1970
0
Discharging once doesn't work, so I figure there has to be
something else that turns into a charge.

If you carry a coin in your hand, grip it tightly between thumb and
finger, and touch the edge of the coin to the checkout counter, you should
feel less of a jolt. The noise may surprise some people, however.
They are leather boots. I don't know what the soles are.

When JMF decided to show off the second to last CPU he worked on,
I had to put a collar thingie around my shoe to prevent an
inadvertant teensy little spark while walking around on the
machine floor. I still don't know exactly what that was. I still
have the shift he had to wear.

Perhaps JMF can get you a bit of the conductive foam that chips are
sometimes shipped in. If you use that instead of the coin, in the way
mentioned above, you should avoid jolts and noisy sparks.

--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

[email protected] remove ch100-5 to avoid spam trap
 
T

tadchem

Jan 1, 1970
0
You probably have plastic or rubber soles on your shoes.

If you had leather soles, the charge would probably leak to the floor
through the shoes.

You could probably modify your shoes to provide a high resistance but still
conductive path to ground.

An Electronic Engineer of my acquaintance used to strip one foot to bare
skin and keep his foot on the tile floor (concrete foundation) while working
on sensitive Integrated Circuits (ICs, such as instrumentation amplifiers).
Some of these had input impedance in the gigohm range, and could be fried by
a spark you couldn't even feel.

I would not recommend that on the bus - OR at the gas pump.


Tom Davidson
Richmond, VA
 
T

tadchem

Jan 1, 1970
0
That doesn't work. I know from experience. I would really
like to find a way to degauss myself at will. I get out of
my car and touch my winter coat-wrapped elbow to the car; get
a poke. I still get a huge poke when I remove the
key from the lock.

Your winter coat could be the problem...

Is it made with a synthetic fiber?


Tom Davidson
Richmond, VA
 
T

tadchem

Jan 1, 1970
0
When JMF decided to show off the second to last CPU he worked on,
I had to put a collar thingie around my shoe to prevent an
inadvertant teensy little spark while walking around on the
machine floor. I still don't know exactly what that was. I still
have the shift he had to wear.

Sound like a grounding strap.

Fuel trucks drag a short chain underneath to provide a path to earth for
static as it is generated. Same principle...


Tom Davidson
Richmond, VA
 
J

John_H

Jan 1, 1970
0
Pharmanaut said:
I thought that in a car it was the air rubbing electron off of the
car, which is insulated from ground by it's tyres, that caused you to be
charged. And that you earth the car to ground as you step out... bloody
painful sometimes!

Vehicles on rubber tyres can certainly become charged, though I'd
suspect the culprit is dust rather than air. In such cases, the
occupants won't be affected while they remain in the vehicle (as
Faraday demonstrated in his classic experiment).

The example given here occurred inside the bus -- ie the occupant
carries the charge relative to the bus. The discharge took place
before the "victim" touched true ground.
 
J

John_H

Jan 1, 1970
0
tadchem said:
Fuel trucks drag a short chain underneath to provide a path to earth for
static as it is generated. Same principle...

One of the worst "vehicles" for generating static electricity
(understandably) is a combine harvester (header).

Many operators drag an earth chain to keep their windows clean!

Experience tells me that it works. :)
 
Sound like a grounding strap.

Yup. That's what it was called; thanks :).
Fuel trucks drag a short chain underneath to provide a path to earth for
static as it is generated. Same principle...

Sure. But a chain is metal and can conduct. I never understood
how this non-metal thingie would work. I'm not sure what the
material was. I thought rubber but then lots of plastic feels
like rubber these days. And the thing only touched my shoe, not
me. The shift's material has a funny feel to it.

/BAH

Subtract a hundred and four for e-mail.
 
One of the worst "vehicles" for generating static electricity
(understandably) is a combine harvester (header).

Many operators drag an earth chain to keep their windows clean!

Experience tells me that it works. :)

Wow! You had windows? ;-)

Charge can be deadly when filling silos.

/BAH


Subtract a hundred and four for e-mail.
 
Your winter coat could be the problem...

Well, I rather ruled that out when I'd get a poke without it
on. Same thing with my boots. I get a poke when I wear shoes.

The instances do diminish in the summer time but then that's
normal.
Is it made with a synthetic fiber?

Yup. What I don't understand is why I don't ground out completely
with the first poke. One of these days, I'm going to remember to
not turn around to lock the car and see if that recharges me. I
know it's a silly notion, but I have to rule out them out, too.

/BAH

Subtract a hundred and four for e-mail.
 
[email protected] wrote in

Some things act as capacitors and may need to be
discharged more than once.

Right. So why can't I manage to get a discharge a second time
through my coat? If I can't do this a second time, then I'm
a walking spark when I pump gas. So far I always lock my car
before I pump gas to make sure I don't spark.


For example, the picture tube of a TV set. The glass of the tube acts as
the dielectric of a capacitor. When you work on a TV, you must be careful
to discharge the high voltage anode connection on the side of the bell.

After the tube has been discharged, as the glass relaxes and as distant
electric charges make their way to the conductive coating inside the glass,
the picture tube will 'build up' a charge again.

It is wise to leave your grounding strap connected for several minutes
before you start to handle the picture tube.

This is one of the many reasons I put hardware on my list as a
"guy thing".

/BAH

Subtract a hundred and four for e-mail.
 
B

bz

Jan 1, 1970
0
Sure. But a chain is metal and can conduct. I never understood
how this non-metal thingie would work. I'm not sure what the
material was. I thought rubber but then lots of plastic feels
like rubber these days. And the thing only touched my shoe, not
me. The shift's material has a funny feel to it.

They include a conductive filler in the plastic when they make it or they
add a conductive coating after the garment is fashioned.

The 'ohms per square' of the material can be rather high and it can still
act as an effective discharge device.



--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

[email protected] remove ch100-5 to avoid spam trap
 
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