Often, a metal underground water pipe of 10 feet or more and in direct contact with the earth is used to supply a building. The plumber installs the pipe and places a 90˚ fitting to turn up the pipe and get it above slab inside the building. Since the water pipe qualifies as a grounding electrode, a grounding electrode conductor (GEC) is installed by the electrician from the electrical service and connected to the water pipe to establish the required grounding electrode system.

For the above, the NEC^® makes it clear that the GEC must connect to the water pipe within the first 5 feet of the pipe after it emerges from underground. Connecting the GEC to the water pipe at a point greater than 5 feet from where the piping enters the building is a code violation.

Bonding water piping systems is different than using the water pipe as an actual grounding electrode. Sometimes, metal water piping serving a building may not be in contact with the earth for 10 feet or more and does not qualify as a grounding electrode in accordance with 250.52(A)(1). The water piping still needs to be bonded per 250.104(A). This bonding can be done anywhere along the metal water piping system and is not required to be done within the first 5 feet where the piping system enters the building.

Section 250.68(C)(1) makes it clear that interior metal water piping used to extend the GEC connection to a metal underground water pipe electrode must be electrically continuous with the metal underground water pipe.

Below is a preview of the NEC^®. See the actual NEC^® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2020 NEC^® edition of NFPA 70.

2020 Code Language:

250.68(C) Grounding Electrode Conductor Connections.

(1) Interior metal water piping that is electrically continuous with a metal underground water pipe electrode and is located not more than 1.52 m (5 ft) from the point of entrance to the building shall be permitted to extend the connection to an electrode(s). Interior metal water piping located more than 1.52 m (5 ft) from the point of entrance to the building shall not be used as a conductor to interconnect electrodes of the grounding electrode system.