What you don't know about grounding can hurt you

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By Del Williams

PlantServices.com

Keywords: grounding, power, electricity and energy

New testing technologies will help your plant avoid unchecked grounding issues.

Aging or unchecked grounding raises the risk of data/equipment loss, process anomalies, plant shutdown and more. Smart Ground Testing minimizes these risks while overcoming traditional grounding test flaws.

Thirty years ago, Hank Aaron was still playing baseball, the first programmable pocket calculator became available, and the word "internet" appeared for the first time in print. Unless your plant still uses the identical technology it did 30, 20, even 10 years ago (when Google didn't yet exist), then trusting your plant's operation to a grounding system installed decades ago - or testing it with a technology developed 80 years ago - isn't perhaps the wisest choice.

What you don't know about your industrial plant's grounding could not only hurt you, resulting in loss of life, but can cost you lost data and equipment as well as slowing processes or halted production. No industrial facility manager would consider violating fire code for fear of the consequences. Yet in too many plants, the foundation for all things electric - the grounding system - is allowed to go out of spec due to aging, corrosion, facility and soil changes, as well as infrequent/inadequate grounding test evaluation. But out of sight does not mean out of danger when it comes to grounding.

"Failing to properly evaluate and fix grounding problems can not only result in unnecessary lightning and transient damage, but also data/equipment loss, process anomalies, plant shutdown, as well as increased fire and personnel risk," explains Joe Lanzoni, a manager with Boulder, Col.-based Lightning Eliminators & Consultants, Inc. (LEC), a firm specializing in electrical grounding, surge suppression, and lightning protection. "Particularly susceptible to these disruptions are plants with sensitive computer, communication, and process control equipment, requiring low grounding impedance from one to ten ohms to work properly."

Proper grounding is the first line of defense against the $1 billion spent annually on damage around the globe due to lightning and 60% of system outages due to lightning on the East Coast alone. Power surge protection equipment also depends on good grounding to defend against power surges and spikes as well as diverting lightning discharges of up to 400,000 amps to ground. Many US industrial grounding systems are in poor repair and the limitations of traditional grounding system testing are hindering efforts to resolve the problem.

Fortunately, there are technologies being designed to keep up with technical advances in the manufacturing and process control industries. Improved ground system testing methods, such as Smart Ground Testing, are now offered by consulting firms such as LEC, which has over 30 years of engineering experience originating in NASA and the US space programs. Any facility experiencing equipment, process, or production anomalies could benefit from a grounding evaluation to determine if it is a possible source of the problem. In fact, any facility without a recent grounding evaluation could benefit, especially those involved in manufacturing, process control, or with sensitive electronic equipment or data centers.

Industrial Grounding Systems Deteriorating
In many cases, the grounding rods in US industrial plants have exceeded their usable lifespan of 30 years because they haven't been properly tested or maintained since installation decades earlier (some pre-date WWII). Out of sight unless dug up, the grounding rods and connectors of these buried grounding grids typically suffer corrosion and undetected electrical discontinuities - causing dangerous faults, processing errors or shutdowns. The problem is especially pronounced in the low resistivity soils near coasts and waterways, which accelerate corrosion.

"Existing grounding capacity is often compromised when contractors dig up or sever grounding wires when burying pipe or telecom cables," adds Lanzoni. "Plant changes and expansions just aggravate the problem when grounding isn't tested and upgraded to meet facility or equipment demands."

These grounding problems often continue for years, causing electrical problems, equipment failure, and even risking personnel electrocution from ground faults that are not safely conducted into the earth through the grounding system.

Until recently, even when facility managers tried to resolve grounding problems, the drawbacks of traditional ground system testing have stood in the way.

The Limitations of Traditional Ground System Testing
Clamp-on ground resistance testers, although convenient, should be limited to testing power distribution poles and residential grounds. Their primary weakness is that their accuracy suffers -- to the point of displaying nothing or a meaningless number -- if resistance is low or a ground loop is present. The grounding electrode being tested must also be parallel with a large number of other electrodes, which is not always practical.

Three-point Fall-of-Potential (FOP) ground resistance testing, which has been used for over 80 years without much advancement, also has significant limitations. Using the FOP test, the grounding system being tested must be disconnected from the equipment being grounded, de-energized, and isolated - but this can be impossible to do in an operating industrial facility where output and processes must be maintained. Because FOP testing doesn't detect grounding discontinuities, the actual grounding rods and connectors to be examined must be physically dug up. Given how expensive and time-consuming this is, checking for grounding discontinuities simply isn't done on a routine basis.