Q. My interpretation of 250.52(A)(3), Concrete-Encased Electrode, is that you must install something in the footing or foundation to complete bonding. If I have footings or a foundation that do not consist of bars or rods in the concrete or they do not meet the minimum requirements, I must install 6.0 m (20 ft) of bare copper #4 AWG conductor. Is this interpretation accurate?

A. The grounding electrodes described in 250.52(A)(1) through (A)(7) are required to be incorporated into the grounding electrode system where they are present at a building or structure being supplied by a service or feeder.  If the electrode types described in 250.52(A)(1) through (A)(3) are not present, it is not mandatory that they be provided or created.  More specifically to your question, if there is no reinforcing steel in the footing or foundation, or if the amount or size of the rebar does not meet the minimums established in 250.52(A)(3), it is not required to create a concrete-encased electrode by either adding rebar or by installing the 20 feet of bare copper wire.  The presence of a footing or foundation at a building or structure does not trigger mandatory use of a concrete-encased grounding electrode as part of the grounding electrode system. Similarly, where a building is supplied by a plastic underground water main, it is not necessary to install metal piping in order to create an underground metal water pipe type electrode.  250.50 is written to address the case where the building structure or mechanical system type electrodes do not exist; it is then necessary to use one or more of the electrode types specified in 250.52(A)(4) through (4)(8).