Conductors Bonding and Grounding

The basic principles of bonding and grounding 2 conductive bodies are shown in the Figure.

Bonding is connecting two or more conductive objects with a conductor, such as a copper wire, that equalizes the potential charge between them, i.e. the voltage difference between the 2 objects is reduced to zero. Bonding is also connecting various parts of equipment and containers that are electrically separated by, for example, gaskets or caulking compounds. Note that bonding does not eliminate the static charge.

Grounding is connecting one or more conductive objects directly to the earth using ground rods, cold water copper pipes, or building steel. Unlike bonding, grounding drains the static charges away as quickly as they are produced.

Static grounds must not be made to:

• electrical conduit systems
• plastic pipes
• gas or steam pipes
• dry pipe sprinkler systems
• lightning rods

Connectors for bonding and grounding, such as copper wire and clamps, must provide a good conductive path. To ensure this:

• remove all dirt, paint, rust, or corrosion from areas where connections are to be made
• use connectors that are strong enough for the job
• use flexible connectors where there is vibration or continuous movement
• connect metal to metal

When charging solids with a non-grounded and conductive chute, a build-up of charges on the chute may occur. This charge can accumulate and finally produce a spark which may ignite a dispersed and flammable dust. Solids can be transferred safely by bonding and grounding all conductive parts and/or using non-conductive parts (drum and chute). For solids with flammable vapors present, handling under an inert atmosphere is required.

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