Static electric discharge & cars

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

Reply to
DaveC
Loading thread data ...

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.

Reply to
James Sweet

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.

Reply to
Archimedes' Lever

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?

Reply to
Sparky

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!

Reply to
CellShocked

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

Reply to
Sjouke Burry

Ah, the answer I was looking for. Thanks!

Reply to
DaveC

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.

Reply to
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.

Reply to
James Sweet

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

Reply to
krw

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)

formatting link

void _-void-_ in the obvious place

Reply to
Boris Mohar

Absolute myth.

CITE!

Reply to
Archimedes' Lever

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.

Reply to
Archimedes' Lever

t -

THE LITTLE IDIOTIC TROLL SWEARS HE KNOWS WATTS UP

I AM PROTEUS

Reply to
Proteus IIV

AlwaysWrong, so wrong, always.

Reply to
krw

d

xt -

YUP WATCH YOURSELF TOO

I AM PROTEUS

Reply to
Proteus IIV

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.

Reply to
Hope for the Heartless

t

FUCK YOU AND YOUR BUTT FUICKED DOT GOV ADDRESS

I AM PROTEUS

Reply to
Proteus IIV

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.
Reply to
Pieyed Piper

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.