Why Do Shopping Carts Shock People?


If you’re like most people, you’ve headed to the nearest Wal-Mart or grocery store, pulled out a cart and felt that all too familiar “zap.” Perhaps you were even zapped periodically as you walked through the store. What gives? Does this only happen on windy days or is there some other scientific reason for this shocking problem?

The story often goes like this: You walk into a store, you grab a cart and start your shopping list with a plan. You’re going to either work your way down your shopping list or you’re going to hit every aisle. As you put your hand on the cart, you feel shock #1. A few minutes later, you take your hands off the cart to grab an item and place them back on the cart, and then bam, you’re shocked a second time.

By the time you head to the checkout line, you’ve been shocked several times. However, there isn’t a storm outside, so what’s the story? Did you find an unlucky cart? Is it just not your day?

Science Behind Shocking Carts

For starters, this problem is nothing new and you are NOT alone. No, it has nothing to do with you, it’s a cart problem. Many stores, especially the major chains with stores all over the country like Wal-Mart have received complaints about shoppers being shocked by carts.

If you can recall your studies in physics, it can help explain the problem. As you push the cart through the store, the wheels on the cart generate friction and static electricity. Rubber wheels on carts are insulators, which means the static is held in the metal cart until it touches something else that’s grounded – you. At that point, the static electricity is discharged and you’re shocked.

Some chains, fortunately, have found a simple fix that you may have never noticed before. Many stores have added a small metal wire to the cart, which hangs down to the ground. This small wire provides a path for the static to travel without having to go through the shopper. Next time you hit the store, look under the cart for this little drag wire!

Next: Hazards Outside the Home

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