Why Your Car Zaps or Shocks You

car zaps or shocks
It might be painful when your car zaps you with static electricity, but it actually isn't dangerous. Zero Creatives / Image Source / Getty
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Question: Why does my car zap or shock me?

My car keeps zapping me all the time, and I’d really like to do something about it. Is there some kind of common reason for a car to constantly shock you, like a short somewhere in the electrical wiring? I’ve never really gotten hurt that bad, but if there’s way to stop my car from shocking me, I’d really like to try it.

Answer:

There are really two ways for a car to “zap” someone, and both the sources and solutions are totally different for each.

The most common reason that people get shocked by their cars is static electricity. This can happen any time you touch metal on the car, but it’s more common right after the vehicle has been driven.

The other way to get zapped by a car is to inadvertently act as an attractive ground for the ignition system, which can be both painful and dangerous. The other electrical systems in most cars aren’t dangerous, or even capable of shocking you, with the notable exception of electric and hybrid vehicles.

The How and Why of Automotive Static Shock

When you touch your car door handle, door, or any other metal surface, and you feel a shock, the cause is almost invariably due to a sudden discharge of static electricity. This is the exact same phenomenon behind the old trick of shuffling your feet on a carpeted floor before touching an unsuspecting victim’s neck to shock them or magically sticking a balloon to something after rubbing it on your sweater.

Static electricity is generated when an electrical charge is built up in one substance as a result of rubbing against another material. In the case of the old feet-shuffling trick, the two materials in question are carpeting and your feet. In the case of a car that consistently zaps you after driving it, the materials are typically your clothes and the seat of the car, which naturally rub together while driving.

If your clothing and the car seat exchange enough electrons, and one side of the equation builds up enough static electricity, it can discharge when you touch your car door or handle. This phenomenon is much more common during periods of very dry weather, as static electricity is able to naturally discharge into moist air, but dry air leaves it nowhere to go.

Certain fabrics and some types of seat coverings are more likely to generate static electricity.

In addition to zapping you when you get in or out of your car, this type of static electricity discharge also presents a very real, if extremely unlikely, safety concern every time you fill up your car. There is actually a kernel of truth in the old urban legend about static electricity igniting gas fumes.

Preventing a Car From Zapping You

There are three main ways to prevent static shock when getting in or out of your car. Two of them involve preventing static from building up, and the third is a way to safely discharge any static electricity buildup without any painful zap.

One way to prevent any static electricity from building up in your clothes while you are driving, or when you slide across the seat to exit the vehicle, is to spray the seats with an anti-static product.

This may or may not be safe for your seats, depending on the materials the seat coverings are made of and the makeup of the spray you choose, so it’s very important to find a compatible product and test it on a small, discreet area first.

The way that anti-static sprays work is that they essentially create a barrier between the surface of the seat and your clothes. Since static electricity only builds up when electrons pass between two materials and create an imbalance, the thin coating of anti-static spray prevents a charge from ever building up. And since there’s no charge, you’ll never get zapped.

Another way many people choose to deal with this issue is to install a static strap. These products are straps that you bolt to the frame or some metal component of the undercarriage of your vehicle. When properly installed, the strap hangs down and contacts the ground beneath your vehicle.

The main drawback of static straps is that installing one results in a clearly visible strip of material hanging down from the bottom of your vehicle, which some people find less than desirable.

The last way to prevent your car from zapping you is to buy an anti-static keychain. These devices provide a safe, painless way to discharge any static built up in your clothes before you touch your door to get out. They typically also include some kind of display or a light that flashes when static electricity is discharged through it.

Other ways to deal with this issue are to first touch the car with your knuckles, which are typically less sensitive than your fingertips, or to use your elbow or shoulder to close your door.

The Shocking Dangers of Automotive Electrical Systems

The other way that a car can zap you is if you’re poking around under the hood and you somehow come into contact with the high voltage passing through the ignition system. While the battery in your car is low voltage, and incapable of shocking you under normal circumstances, that voltage is stepped up in order to operate the ignition system.

Ignition systems require higher voltages because of the way that air/fuel mixtures are ignited inside internal combustion engines.

This process relies on spark jumping across an air gap between two electrodes built into a small component that is inserted into each combustion chamber. These components are called spark plugs because they are literally plugs that have two electrodes across which a spark jumps.

In older engines that make use of distributors, the voltages involved are high, and definitely capable of zapping you if you touch the wrong thing, but they usually aren’t dangerous. The higher voltages involved in distributor less ignition systems are more likely to cause injury, but it’s a good idea to just avoid getting shocked by either type of system.

Most ignition system shocks are the result of a malfunctioning component, like a spark plug wire that has frayed due to age or proximity to a sharp object or hot surface. This type of malfunction often leads to an engine that doesn’t run very well, as the wire ends up shorting out and delivering its charge straight to ground rather than to its spark plug. If you insert yourself into the equation, you’re likely to get shocked.

The best way to avoid getting shocked by an ignition system is to just be very careful around the ignition components whenever the engine is running, and replace any worn or malfunctioning components.

It’s important to note that hybrid and electric vehicles typically use much higher voltage electrical systems than conventional cars and trucks. So while it is possible to be shocked by one of those systems, they typically have high voltage wires that are marked carefully to help you avoid them.