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Interesting; last week I was at one of the Costcos I visit frequently, and I had the same experience (which has NEVER happened before, and I've been shopping there since the mid 80's).? The charge would build up very quickly (maybe 6-8 steps), then discharge between my hands/fingers and the plastic grip of the cart.? Most of the time it discharged while I was gripping it, not when I let go and re-grasped it.? It seemed like it was building up a charge until it could overcome cracks in the plastic or ???.? No discharges onto other metal surfaces.? Same old shoes/jeans etc.? Outside the store in the parking lot everything was normal.
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-Dave On Saturday, May 4, 2024 at 09:31:40 AM PDT, cheater cheater <cheater00social@...> wrote:
Hi all, I frequent a large grocery market nearby and inevitably every time I go there I get electrical shocks. I walk around with a cart and often if I touch a metal fixture (fridge, mesh rack) I get a painful shock. Sometimes I get a shock if I leave the cart for a few seconds and then touch its metal mesh. I was wondering what everyone thought. At first I thought it would be ESD, but why would it be so extreme? It happens every time. I live in a place that's pretty dry - RH goes under 20% regularly - and being on a plain it has a lot of wind, which could create triboelectric charging. But I'm not really sure about this. I don't know which way the ESD happens. Is my body discharging into the cart? Is the cart discharging into my body? Is my body discharging into the racks or vice versa? How can one check the directionality of ESD? One theory about ESD I have is that the fixtures get charged and my body gets the charge applied to it. This however isn't necessarily true to me because eg today I got a painful shock from touching the inside metal surface of a fridge, and that's supposed to be earthed. Another theory is that as I walk around in the store, as I move around with the cart, that charges my body. I wear rubber sandals and the cart has rubber wheels. That would mean I'm a conductor, attached to a large antenna (the cart's mesh frame), moving through dry air, insulated from the ground. The ground is made out of some sort of high impact ceramic-ish tile. But then why would my own cart shock me just mere seconds after letting go of it? I was unloading my groceries for the cashier. My third theory is that this whole facility has a lifted earth potential. There's an industrial area nearby and they may be dumping a lot of current into earth which would create a situation where walking on the ground charges you, and then touching something that's low-Z to neutral discharges your body (in this case this would be the earthed fridges etc). I was wondering how people would approach diagnosing this problem, and how you would fix it if you had the ability to change anything about the facility at hand - more as a thought exercise, but if I figure out what's going on I'm going to write to the company. Thanks |
