During a recent presentation on flammable and combustible liquids, I was asked about grounding and bonding requirements while dispensing flammable liquids with a flashpoint of 99 degrees Fahrenheit and below. Stewart R. Browne Manufacturing (770.993.9600) has an excellent document “Grounding and Bonding Applications for Control of Static Electricity” that describes (with illustrations) grounding and bonding requirements. With respect to maximum resistance with the grounding and bonding connections, Stewart R. Browne Manufacturing states the following:

“The design and installation of bonding and grounding systems requires careful attention that a continuous, low resistance path is established to remove charges from all parts of process equipment. The resistance of this path should be no more than 25 ohms to avoid static build-up to a dangerous level.” Click here to download the document (note: link is under grounding and bonding section).

Whenever grounding and bonding cables are installed they should be tested during initial installation, after repairs/damage to equipment, and at least annually with an electrical multimeter to verify there is no more than 25 ohms resistance between connections.

Jon