Water Pipes for grounding
Water pipes have been used extensively in the past as a grounding electrode. Water pipe connections are not testable and are unreliable due to the use of tar coatings and plastic fittings.
City water departments have begun to specifically install plastic insulators in the pipelines to prevent the flow of current and reduce the corrosive effects of electrolysis. Since water pipes are continuous city wide, fault conditions in adjacent neighborhoods could backfeed current into sensitive equipment causing unintentional damage.
The NEC requires that at least one additional electrode be installed when using water metal pipes as an electrode.
There are six several additional requirements including //
- 10 ft of the water pipe is in direct contact with the earth
- Joints must be electrically continuous
- Water meters may not be relied upon for the grounding path
- Bonding jumpers must be used around any insulating joints, pipe, or meters
- Primary connection to the water pipe must be on the street side of the water meter
- Primary connection to the water pipe shall be within 5 ft of the point of entrance to the building
Reference // Standard Handbook for Electrical Engineers By Donald G. Fink, H. Wayne Beaty (Get it from Amazon)