Static electric discharge & cars

[DaveC]

This gas station security video:

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>

and this Mythbusters episode:

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>

discuss the dangers and the how-and-why of static electricity and refueling
your car.

My question is regarding how to safely discharge such a charge.

The guy from the refueling equipment industry who is interviewed in the
Mythbusters' episode says that simply touching the car body when exiting the
car is enough to discharge your body's static charge.

But isn't the fact that the car is on rubber tires and you (in this
worst-case scenario) are wearing non-conductive shoes, you are not going to
provide a ground at all? Yes, you will equalize the charge with the car, but
the danger still remains when you reach the nozzle sticking out of your car's
filler door that is when the spark will occur (presuming that the nozzle has
some grounding lead?).

Help me understand the possible safe paths to ground in this scenario.

Thanks,
Dave

 

[James Sweet]

This gas station security video:

<

>

and this Mythbusters episode:

<

>

discuss the dangers and the how-and-why of static electricity and refueling
your car.

My question is regarding how to safely discharge such a charge.

The guy from the refueling equipment industry who is interviewed in the
Mythbusters' episode says that simply touching the car body when exiting the
car is enough to discharge your body's static charge.

But isn't the fact that the car is on rubber tires and you (in this
worst-case scenario) are wearing non-conductive shoes, you are not going to
provide a ground at all? Yes, you will equalize the charge with the car, but
the danger still remains when you reach the nozzle sticking out of your car's
filler door that is when the spark will occur (presuming that the nozzle has
some grounding lead?).

Help me understand the possible safe paths to ground in this scenario.

Thanks,
Dave

The biggest issue is the discharge between you and the car. I always
touch the metal door frame as I get out in the winter because I hate the
powerful zap that I often get otherwise. If you are really paranoid,
touch the metal gas pump and the car before you stick the nozzle in, but
it really shouldn't be an issue. While fires can and have been caused
by static, it really is extremely rare in perspective, maybe one every
few years, compared to 50,000 Americans killed every single year in car
accidents. You hear of more people killed being struck by lightning than
fires from static while pumping gas.

 

[Archimedes' Lever]

This gas station security video:

<

>

and this Mythbusters episode:

<

>

discuss the dangers and the how-and-why of static electricity and refueling
your car.

My question is regarding how to safely discharge such a charge.

The guy from the refueling equipment industry who is interviewed in the
Mythbusters' episode says that simply touching the car body when exiting the
car is enough to discharge your body's static charge.

But isn't the fact that the car is on rubber tires and you (in this
worst-case scenario) are wearing non-conductive shoes, you are not going to
provide a ground at all? Yes, you will equalize the charge with the car, but
the danger still remains when you reach the nozzle sticking out of your car's
filler door that is when the spark will occur (presuming that the nozzle has
some grounding lead?).

Help me understand the possible safe paths to ground in this scenario.

Thanks,
Dave

As your car moves through the air, it gathers ions from the air, which
are excess electrons that happen to be tagging along on an air molecule.

This charge builds. As you exit your car, you also acquire this level of
charge, and depending on how moist your socks are, and how much moisture
your shoes contain, and what their soles are made from, you retain a
certain amount of that charge.

So the only thing touching you car does, if anything, is to actually
charge YOU up along with it, since both elements (you and your car) are
both insulated from the ground. This problem gets exacerbated further in
the bed liner scenario as the can itself can attain an even higher
charge, being fully insulated from any discharge points.

So, the procedure, in ALL cases is to balance the charges on all
elements of the system (YOU, THE CAR, AND THE PUMPS, AND GROUND).

We use ground as our baseline, and for good reason. The earth weighs
gazillions of Gigatons, and that is about as balanced at zero as it gets.

So, you walk up to the pumps, and spot the stainless steel strips they
use as edging, or other decor on the pumps, and you touch it. While
touching it, you touch your car. Now, you, your car, the pump, and
ground have all been brought to the same level of balance between each
other, and ground as well.

No chance for any further arcing, unless the fuel is gaining a charge in
today's, modern, 100% insulative polymer tank linings, but I doubt that
scenario.

With the bed liner scenario, be sure to also add touching *that* tank
as well, while touching the pump.

THEN you can remove the handle, initiate the pump works, and begin
pumping gas into a can or tank of your car.

A boat on a trailer should also be touched, while touching the pumps,
and before opening the fuel tank lid.

That is the extent of the measures you can take short of wearing a heel
strap from the electronics industry, that keeps you dissipated at all
times (when on a grounded, conductive surface) at ground reference.

 

[Sparky]

A related question: Is the dispensing nozzle grounded?

If the answer is "yes", then the driver simply can touch any bare metal (on
the car, the pump, anywhere) to discharge static.

Anybody know the answer?

 

[CellShocked]

A related question: Is the dispensing nozzle grounded?

If the answer is "yes", then the driver simply can touch any bare metal (on
the car, the pump, anywhere) to discharge static.

Anybody know the answer?

Why would you want THAT location to be a point of arcing?

How stupid is that?

NO. You use your BODY to discharge things. The pump, and the
dispensing nozzle are already grounded. YOU need to ground the car or
any other tank or metallic device you want to contact with the pump,
BEFORE you go near it with the pump NOZZLE.

What idiot would use the delivery end of the nozzle for a flammable
liquid, as the discharge point for a static electric discharge?

Even if it is before you begin delivery, there are remnants of fuel in
the nozzle, and why temp fate to begin with?

DOH!

So, the answer is YES, it is grounded, but NO one does NOT use it to
discharge static ANYWHERE EVER!

 

[Sjouke Burry]

A related question: Is the dispensing nozzle grounded?

If the answer is "yes", then the driver simply can touch any bare metal (on
the car, the pump, anywhere) to discharge static.

Anybody know the answer?

There is a nice fat wire inside the feed tube.
If not,your licence to sell fuel is revoked.

 

[DaveC]

There is a nice fat wire inside the feed tube.

If not,your licence to sell fuel is revoked.

Ah, the answer I was looking for. Thanks!

 

[James Sweet]

And the car is grounded all the time by the carbon black in the tyres.
(Oh tires for the other people).
The resistance is quite high but adequate to keep the vehicle at ground
potential.

John G.

I don't think that's the case. I have a Van De Graff generator that uses
a black rubber belt and it generates something in the range of 100KV
which would drain through the belt if it was conductive. You can also
get those ground straps that dangle from the underside of the car to
keep static discharged. If the car were always at ground potential, this
problem wouldn't exist in the first place.

 

[krw]

And the car is grounded all the time by the carbon black in the tyres.
(Oh tires for the other people).
The resistance is quite high but adequate to keep the vehicle at ground
potential.

Not so much anymore. I've often gotten zapped getting out of my
truck.

 

[Boris Mohar]

Not so much anymore. I've often gotten zapped getting out of my
truck.

This happens when you slide across the seat to get out. Especially in
winter. Hold the door frame when getting out and your hair will not stand on
end.



Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca

void _-void-_ in the obvious place

 

[Archimedes' Lever]

And the car is grounded all the time by the carbon black in the tyres.

Absolute myth.

CITE!

 

[Archimedes' Lever]

Not so much anymore. I've often gotten zapped getting out of my
truck.

It isn't a true statement, even when referencing '50s tires.

Maybe lightning conduct across it, but not much else.

Lightning >6MV

ESD discharge < 20kV, probably higher on a good day.

 

[krw]

It isn't a true statement, even when referencing '50s tires.

AlwaysWrong, so wrong, always.

 

[Hope for the Heartless]

And the car is grounded all the time by the carbon black in the tyres.
(Oh tires for the other people).
The resistance is quite high but adequate to keep the vehicle at ground
potential.

Unless you drive the car. Rolling the car across the ground generates
static electricity. Also, the potential at one ground location does not
equal that at another location, and the car picks up charge from the
wind as well.

Never assume the car is grounded until you have discharged it to
something you know is grounded.

 

[Pieyed Piper]

the potential at one ground location does not
equal that at another location,

This is bullshit. While it is true that grounding systems for
electrical power fault returns, etc. "see" differing levels of
"resistance" in their installations, you can bet that pretty well the
entire planet is at the same potential as it relates to sinking a static
charge, and only very specific, select areas would have some different
"value" with respect to the other
99.9999999999999999999999999999999999999999999% of the planet.