How to Ground Materials and Carts to ESD Floors
Q: How do I ground non-esd materials and carts to a conductive tile floor?
A: Add conductive drag chains and casters to materials and carts to ground them to esd flooring.
The photo to the right shows a recently completed Conductive Vinyl
tile installation. This client plans to use "wire shelf carts" to move
electronics assemblies around the floor. Even though this floor is
grounded and conductive, the cart will not be grounded as its wheels
are insulators. Static cannont drain through an insulator even if that insulator is resting on an esd, anti static floor. The cart shown in the
photo does not have a conductive drag chain or conductive casters.
Adding conductive wheels or drag chains to the cart provides a path for charge in the cart to drain to ground, in this case the conductive floor.
More on insulators
An insulator can never be grounded as the properties of an insulator are inherently non-conducting.
Examples of common non-conducting materials are:
- A pot holder used to separate skin from a hot pot or pan in a situation involving heat
- Plastic around a wire, making it "safe", in a situation involving electricity.
Floating conductors
In the case of the cart with no ground chain or conductive castors and the ESD floor, pictured above, the cart is classified as a "floating conductor" as its insulative wheels are insulating it from ground. What is a floating conductor? Any conductive object that is electrically separated from ground. In the example above, the floor is considered ground. Another example of a floating conductor is people wearing regular footwear and no heel straps walking on an ESD floor.
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