February 19, 2007
By Steve Fowler, Publisher
We are reminded everyday of static electricity.
When we go shopping many times the action of rolling the
cart across the floor generates high potentials. Then
we get zapped as we reach for the can of peas. Most stores
do little or nothing to make this problem better. Some
of the larger discount stores are the worse offenders.
one grocery store chain has finally taken a stand on getting
the static potentials reduced. Food Lion has begun to
put drag wires on the carts.
floors are not static dissipative but they are on grade
level and over concrete. The use of wires instead of chains
was a good idea. Even though the floors have little surface
conductivity, the pointed wire helps connect to what conductivity
is there but more importantly the wire can corona ionize
the cart to the concrete with very good effects.
This author performed a very unscientific
experiment at the Food Lion. One has to be careful not
to look suspicious walking through a grocery store these
walked briskly around the store with a cart which had
not wire attached. The humidity was approximately 20%
RH at 70 degrees F during my walk. I achieved almost 8
kV on myself holding the cart.
using a cart with the wire, I could not get above 3 kV
and it drained fairly quickly. Looks like it works.
Remember that a person can not feel a
static shock of less than about 3 kV. This means that
the wire would keep the shocks below most people's threshold
Of course on another day, the numbers
could be higher for the ungrounded cart but I suspect
not for the cart with the wire.
This not only will make shopping there
more comfortable, it will help keep the checkout computer
system from crashing as well as the point of sale credit
card systems from glitching. Not to mention the destruction
of the smarts in "Smart Cards."
Good work Food Lion.