How to specify static-free flooring in different types of spaces

Your engineer is correct on both counts. Some static control carpet tile is extremely conductive (too few ohms resistance) and should be reserved strictly for use in spaces where footwear is controlled and measured for resistive properties. Sometimes these spaces are called EPAs. EPAs are segregated areas inside electronics manufacturing and handling facilities. They are easily differentiated from other spaces requiring a static-free environment. For example, people working in EPAs are required to wear special static-control footwear. Prior to entering the EPA, employees and visitors must test their footwear using a static- control footwear tester. Based on results of the testing, the person is either given a green light permitting entry or is prohibited from entering the area due to the ohms measurement of their shoe soles. Footwear testers sort out people who may be wearing wet shoes that are too conductive. Wet shoes could present a safety hazard if they are worn on a floor that is too conductive. Keep in mind that conductive (25,000 ohms plus) carpet tile can be used in EPAs but it offers no advantage over less risky static dissipative carpet tile.

EPA protocols would never be used in critical environments (CEs) like 911 dispatcher areas, data centers, or networked offices.  Personnel in these spaces wear ordinary footwear in these spaces. For this reason, specifiers must utilize different specification criteria based on whether a space is a CE or an EPA. In the case of carpet, the specification should always err on the side of safety and good judgment.

We recommend that carpets never measure below 100,000 ohms and not above 100,000,000 ohms. Specifying this ohms range eliminates the need for 100% screening of footwear whenever someone enters a critical environment. Using this ohms range will also allow you to address the needs of both an EPA or a cortical environment like a call center.

How to differentiate over conductive carpet from other viable static-control carpet options:

Overly conductive carpet is usually specified as having an ohm’s range beginning at 25,000 ohms, which is also represented as 2.5 X 10E4.  25,000 ohms offers personnel less protection from unlikely electrical shocks due to faulty grounding than 100,000 ohms resistance. 25,000 ohms of resistance is the bare limit amount of resistance approved by NFPA99. Additionally, 25,000 ohms does not meet telecommunications standards Motorola R56 and ATIS for use in applications like call centers and 911 dispatch communication areas.

The right flooring will have a resistance range of over 100,000 ohms. When reading spec sheets, do not assume a floor will meet the needs of the space based on a manufacturer stating that it meets Motorola R56 or ATIS. These claims are often incorrect due to recent changes on these standards. Instead, look at the exact stated ohms range. If it measures below 100,000 ohms, it should not be used in places where communication and computer equipment is plugged in and operating.

If you have concerns about liability risks or whether or not a flooring material meets a specific grounding standard, refer to this chart: