The proper installation of bonding and grounding systems is important in the protection of personnel and property. At the time of installation, a resistance test is needed to confirm electrical continuity to ground. Evaluating the maintenance requirements, the bonding and grounding system can be divided into three categories:
- The point-type clamps equipped with flexible leads used for temporary bonding of portable containers to the building grounding system.
- The fixed grounding cables and bus bars used to connect the flexible leads and fixed equipment to ground.
- The ground rod/electrode itself
The flexible leads are subject to mechanical damage and wear, as well as corrosion and general deterioration. For this reason they should be inspected frequently. This inspection should evaluate cleanliness and sharpness of the clamp points, stiffness of the clamp springs, evidence of broken strands in the cables and solidity of cable attachments. A more thorough inspection should be made regularly using an intrinsically-safe ohmmeter to test resistance and continuity.
One lead of the ohmmeter is connected to a clean spot on the container, the other lead is connected to the grounding bus, metallic piping or other fixed equipment. The measured resistance should be less than 25 ohms and will usually be about one ohm.
The fixed leads and the bus bars are not usually as subject to injury or wear as the temporary connectors. These should be checked with an ohmmeter on an annual basis. One lead of the ohmmeter should be connected to the fixed lead or bus bar, the other lead should be connected to the plant earthing electrode or to the structural steel of the building. The measured resistance should be less than 1 ohm.
Conductive Hoses
Conductive hoses should be checked regularly, and after repair or replacement for electrical continuity and resistance. The conductive segments may break and may not be repaired properly thus rendering the hoses nonconductive or with an abnormally high resistance. Nonconductive hoses having an internal spiral conductor should be installed so that the spiral conductor makes contact with adjacent metallic fittings.
Source: http://www.srbrowne.com/booklet/