I too have dealt with shocks from the cart at my grocery store. I
attributed it to the cart building up charge by rolling. A good test might
be to hang a dragging chain from the cart, but I've never bothered.
Dave Casey
On Sat, May 4, 2024, 7:09 PM Dave Seiter via groups.io <d.seiter=
[email protected]> wrote:
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.
-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
