As testers, where should we start? The standards! For grounding testing, the industry reference is IEEE Std. 81, Guide for Measuring Earth Resistivity, Ground Impedance, and Earth Surface Potentials of a Grounding System. As with most standards, familiarity and interpretation are key. It can be a challenge to understand the intent, methods, and implementation of the prescribed testing. Fall of Potential …
Soil — most think, “Hey, it’s just dirt,” but when it comes to electricity, soil becomes more complex. Electrical resistivity (resistance to current flow) is one characteristic of soil that requires specific knowledge regarding testing and application in grounding system design. Soil is made up of combinations of clay, sand, loam, and various types of rocks. These components have differing …
Everyone has heard stale jokes about not reading instructions until it becomes a last resort. With many electrical test instruments, experience or general familiarity can at least get you started. But with ground testing, taking the new instrument out of the box and trying to figure out how to run the test will get you nowhere. There is nothing intuitive …
Out of sight, out of mind is a common aphorism, but when it’s applied to standby backup batteries, it can — and does — become catastrophic. Standby battery banks support production lines, hospitals, computer rooms, and entire facilities to provide an alternate power source should utility power fail. The standby battery is the interface between a smooth transition and total …
Storms with lightning are a major cause of electrical system interruption.
Grounding and bonding are integral parts of an electrical system and must be properly understood, installed, and maintained for maximum safety and performance. Accordingly, the National Electrical Code© (NEC©) focuses on describing, defining, and regulating this element, specifically in Article 250 Grounding and Bonding of Electrical Systems. Grounding electrical systems serve the dual purpose of limiting voltages that might otherwise …
Utility substations are undergirded by large — sometimes massive — grounding grids. These are made up of electrodes, much like the familiar ground rod, but with extended responsibilities. The grid must provide a means to carry electrical currents into the earth under normal and fault conditions without exceeding operating and equipment limits. The grid must also assure the safety of …
Designing, installing, and maintaining an adequate grounding system is as important a part of substation design and maintenance as any other. “Out of sight, out of mind” definitely does not apply here. The grounding grid is not only essential to proper function and power quality but is also critically important to worker safety as well as that of public passersby. …
The fundamental principles of electrical ground testing were laid down in the early 20th century, with much of the pioneering work done by Frank Wenner of the U.S. Geological Survey. The most basic and widely used method for measuring soil resistivity bears his name. These principles still underlie ground testing into the present century, but many improvements have been made …
Commissioning and maintenance procedures for low-voltage circuit breakers may include testing to determine whether the circuit breaker is able to respond correctly to faults or overload conditions as specified in the coordination study. This requirement may include ground fault (GF) as part of the protection scheme. Testing may be performed through primary or secondary injection; primary injection is the best …