MOST INDUSTRIAL, COMMERCIAL, AND EDUCATIONAL FACILITIES depend heavily on telecommunications, data, and computer networks. In many petrochemical installations, the functions of all three types of facilities are combined into one location. These facilities often experience problems with signal quality and noise on communication lines because of the proximity of highspeed, low-level signals to higher power lines. Additionally, electrical safety and various code issues must be addressed. Topics such as multiple ground systems, connections to ground, potential difference, circulating currents, and wiring methods are discussed. Eleven different systems must be bonded together. Three areas specific to networks require special attention. These are equipment bonding, isolated earth ground, and isolated power systems. Finally, cathodic protection systems have a unique impact on grounding systems.