A few weeks back, my wife went shopping at Wal-Mart and came home with a bunch of groceries and a fantastic story. According to her, it went like this:
She had parked her empty cart at the end of an aisle while she walked away to pick up an item in a crowded section. Upon returning to her cart, she noticed that it was a different cart than the one she had left there. As she went about her shopping with her new cart, she kept getting shocked as she pushed the cart or returned to it. The shocks were also frequent and painful enough that she ended up putting her gloves on to prevent the shocks from reaching her. At this point, she began to get suspicious that her cart hadn’t been replaced accidentally but quite intentionally by the original owners, whom she speculated were fellow shock victims.
Fully gloved, she finished her shopping and loaded the groceries into the car. As she was transferring the groceries, she was approached by a lady walking towards the store asking if she could take her cart for her. My wife felt it was her duty to warn the lady that it had been shocking her throughout the store and it may do the same to her. The lady looked at her as if she were quite crazy and mentioned something about having to call the ‘Wal-Mart Paranormal Police’ if she ended up getting shocked too.
A few weeks later, fast forwarding to this evening, my wife and I went shopping at Wal-Mart again and noticed an odd thing on about a third of the carts:
In the center, at the front of the carts, a simple clip now holds a small wire that dangles from the cart and touches the ground. (You can click on the above image for a larger version of the photo.)
Wal-Mart has apparently received numerous complaints (Consumerist, Yahoo! Answers, KCRA news) and many people have similar stories that echo my wife’s story. (She seems a little less crazy now.) Any high school physics student could tell you the problem. The wheels spin as the cart is pushed generating friction and static electricity. Since the wheels are rubber, an insulator, the static is held throughout the metal cart until it is finally discharged by touching something else that is grounded, e.g. you. By adding the wire to the cart and allowing it to hang to touch the ground, the static is provided a path to ground itself without having to go through the driver.
A simple solution to a common problem and apparently it’s working quite well as there were no shocks on today’s shopping trip despite big, fluffy winter jackets. These little devices may be coming to a Wal-Mart near you. Some may have a different style as this article details a ‘static chain’ attaching to the wheel to ground the cart.
At least we won’t have to call the ‘Wal-Mart Paranormal Police’.