To achieve the electrical specifications for the static control (esd) flooring materials you have selected your floor must be properly grounded. Proper grounding runs the full gamut from simple to technically challenging. Static control floor grounding techniques are important in even the most basic of environments and critical in protected electronic manufacturing environments, explosive, ordinance and munitions environments.
At United Static Control Products, we are specialist in grounding your static control floor to a multitude of requirements from basic to advanced to critical.
Although grounding your esd floor is imperative, most installations now dictate a relatively basic grounding method due to recent advancements inherent in the new higher conductivity adhesives. This basic method is now generally adequate in achieving an installed electrical RTG (resistance to ground) close to the center of the flooring systems electrical conductivity range.
We generally supply (at no charge with your flooring order) a quantity of grounding hardware appropriate for basic grounding in non-critical standard environments. The quantity of grounding hardware we provide is for use with installations utilizing one of our conductive adhesive to concrete substrates. All of our ESD flooring materials are designed to work in conjunction with our permanent one part, water based acrylic liquid conductive adhesive (US C 2000), our unique releasable adhesive "Tape" (URAS), or our NEW US C2004 R Liquid conductive releasable adhesive.
All adhesives provide reliable anchoring of the flooring, as well as a equiplane of fairly high, permanent conductivity (typical between 1.0E02 and 1.0E04) allowing equalization of electrostatic potential for subsequent elimination via ground straps placed into the adhesive and beneath the esd floors.
Your goal when grounding any esd floor is to provide a reliable, long lasting mechanical connection from your ESD flooring and adhesive to a dependable earthed electrical ground in your building and to come as close as possible to the lower middle of the materials specified resistance to electrical ground.
BASIC GROUNDING OF AN ESD FLOOR
A variety substrates may be covered with esd flooring. Non conductive (insulative) substrates will somewhat alter the conductivity of certain flooring, more so with static dissipative materials like ElectraFloor Static Dissipative (that rely mostly on the ambient humidity in your environment for conductivity) than conductive flooring like our UltraStatic ESD control Tiles (that are non humidity dependant).
When covering wood, standard VCT or epoxy substrates additional grounding straps may be required. It's always best to "check RTG as you go" when encountering highly insulative surfaces and adjust the number of flooring grounds accordingly. Conversely, concrete surfaces, devoid of sealers and finishes are inherently conductive.
Although concrete's conductivity will fluctuate dramatically (depending on the ambient humidity of your environment and the moisture content of the concrete) it will always have areas of conductivity, helping to make grounding of your esd floor relatively easy. Our experience has shown that with the static conductive or dissipative non-humidity dependant esd vinyl's and carpeting, covering a cement substrate, only one ground per 2,500 SF is normally required.
When covering insulative substrates or when working with humidity dependant esd floor covering materials 1 ground per 1,000 SF will provide the best results. Always use a minimum of 2 ground points, even in small installations.
Method 1A) Copper foil tape method
One of the most popular methods of grounding is to locate an AC electrical outlet, turn off the power to the outlet. Place 12" of our 2" heavy duty foil into the wet adhesive (directly beneath the outlet), place conductive adhesive over the pre-placed strip (for subsequent covering with the esd flooring).
Extend the remaining 12" up the wall (double sided tape or a dab of adhesive placed on the back of the strip can help hold the strip securely to the wall). Carefully remove the face plate cover of the outlet and loosen the bottom of the electrical plug from its wall retainer. Most electrical outlets have 2 small "ears" at the bottom of the outlet that facilitate as a flush mounting stop.
Carefully remove the center screw (between the ears) and run a section of the copper strap behind the ears (trim as required). Replace the screw, going through the copper foil and pulling the outlet back flush with the wall. Replace the face plate cover and test strap for electrical resistance to ground. For esd floor grounding purposes a reading below 1 ohm resistance to electrical ground is sufficient.
Method 1B) Aluminum foil grounding tape is now highly recommended for use by United Static Control Products.
* Locate AC power outlet. Remove electrical face plate cover (typically plastic). Starting at a location about ½” beneath the outlet cutout (on the drywall) run a piece of our 2" wide aluminum foil ground tape down wall and onto floor about 2 or 3 inches.
Note: for a great looking attachment cut any wall base, peel back base and run strip behind re-glued base.
* Run another aluminum foil strip (about 36” long piece) over this 2" or 3" piece that you've placed on the floor. Run this strip parallel to the wall and stick to the concrete.
* Cover this strip with conductive adhesive and install flooring as recomended.
* Replace plastic AC electrical face plate cover with a metal face plate cover making sure metal face plate cover contacts the aluminum strip.
* Your floor is now grounded.
Another popular method of grounding an esd floor utilizes the same quantity and type of esd copper or aluminum foil. In method 2 the foil may be terminated where convenient.
With approximately 8" of the copper foil placed into the wet adhesive and 8" running up the wall to a heavy gauge copper grounding bus terminated to the building AC electrical ground via electrician installed cabling.
Useful on large floors or floors where an ac outlet or grounding bus is not available relies on the use of steel columns, water pipes and other permanently grounded structural items for grounding terminations.
First, check the electrical resistance of the item, clean connection point as needed to achieve <1ohm between item and AC electrical ground. Permanently attach copper or aluminum strip (see drawing 2).
adhesive, prior to covering with esd
In this sketch
a steel column