Is 'bare concrete' is the best "anti-static" flooring?

This question has as much to do with aesthetics, as it has to do with static control performance. Obviously if you are asking this question about your current facility, you are the only person who can answer the impact bare concrete has on the impression your floor will have on customers and visitors. However, from an electrical perspective, there are several factors that should be carefully considered. 

1. Bare concrete can provide excellent electrical properties capable of meeting S20.20. I have measured the conductivity of some concrete that I found to be too conductive only to see that same concrete measure almost insulative during the span of the same year. This broad performance differential would be a hard sell to a knowledgeable auditor (or customer) as part of any ISO certification process. Bare concrete with high conductivity usually means a damp and often musty building.

2.The electrical resistance of bare concrete will usually vary up to 2 orders of magnitude in either direction.

3. Bare concrete will often absorb vapor from the soil below and become dangerously conductive.

4. If you choose to stick with bare concrete you should test the resistive properties of your floor with an ohmmeter on a regular basis.

5. We strongly suggest performing ESD S 97.2 body voltage tests to determine if the bare concrete will maintain voltages below 100 volts.

6. If you use any areas of the factory for "hi pot" testing you should procure and install rubber insulating mats to protect your personnel from possible electrical shock hazards.

7. You need to set an absolute minimum flooring resistance. We strongly suggest 100,000 ohms for a factory environment and 1,000,000 ohms for an operational equipment environment.

These videos might help you expand your research:

• ESD Flooring: Static Dissipative vs. Static Conductive
• Testing Your ESD Floor
• Making Sense of ESD Standards for electro static discharge problems
• ESD Grade Flooring Could Be Too Conductive