Grounding Electrode System and Grounding Electrode Conductor Part III zNEC 250 (Grounding Electrode System) 250 Electrodes Water Pipe if 10 ft. or more of metal water pipe is in contact with the earth. Metal Frame of the Building or Structure where the following methods are used to make an earth connection: (1,2,3,4) Related searches for circuit diagram grounding residential service grounding diagrambuilding grounding system diagramsub panel grounding diagramhome grounding system diagramtransformer grounding diagramgrounding and bonding diagramelectrical panel grounding rod diagramnec grounding requirements diagrams