Selection of ground rods: What are the determining factors?

[HuskyFC450]

Customer has approximately (15) small "CONEX" lockers scattered on a paved lot. Each of these small storage containers have various types of commercial/industrial hazardous waste materials inside (ballasts, fluorescent lamps, empty spray paint cans, batteries, etc.} A few of these metal containers have been grounded with an individual ground per container (don't know why since there is no electrical service or electrical connections to any of these containers}. If by chance, there are requirements to ground such enclosures, how would I select the correct dimension of ground rod, i.e. 1/2" x 8' or 5/8" x 10' etc?

Tom

 

[EnergyProfessional]

I'd say they need it for lightning protection.

Your grounding should be designed to have less than 25 ohm. Obviously this varies with moisture etc. so design on the safe side, measure resistance and add rods as needed.

this depends largely on rod depths, and soil. your 10'rod could be OK. You may encounter rock less than 1-'or have very dry soil and then you need more rods or need to drill through rock.

 

[stevenal]

I suspect some of your hazardous materials might be flammable. Grounding is to help avoid static buildup. High voltage and low current mean resistance can be fairly high. I would expect the grounded containers to be marked in some way, though; so that flammable materials don't end up in the wrong container. [URL unfurl="true"]http://armypubs.army.mil/doctrine/DR_pubs/dr_a/pdf/fm10_67_1.pdf
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