Ground Testing Procedures

Jeffrey R. Jowett Columns, Tech Tips, Winter 2020 Columns

Effective ground testing is an informed combination of instrumentation and procedure. Accuracy, resolution, safety, noise suppression, graphics, clamp features, and general reliability are all critical, as they are with any electrical testing. But effective and accurate ground testing depends as much on adherence to procedure as it does on quality of instrumentation. If the operator does not understand and diligently …

Medium-Voltage Grounding

Jeffrey R. Jowett Columns, Fall 2020 Columns, Tech Tips

First, let’s look at some industry-accepted definitions to establish context. Low voltage is anything below 1 kV. The common building-wiring voltages are 120, 240, 480, and 600 V. To the uninitiated, this can seem confusing and even ridiculous. Get across 600 V, and it can fry you like bacon, but in industry parlance, it is still low voltage. Put into …

Tracing Ground Leakage with a Clamp-Meter

Jeffrey R. Jowett Columns, Summer 2020 Columns, Tech Tips

The clamp-on current meter that appeared in the late 20th century was a blessing to everyone working in electrical testing. It improved the vital measurement of one of the three components of Ohm’s Law by a quantum leap. No more difficult, costly, time-consuming, and potentially dangerous direct connections to live circuitry. Just clamp a pair of jaws around a conductor …

Monitoring a Grounded System

Jeffrey R. Jowett Columns, Spring 2020 Columns, Tech Tips

Electrical faults cause enormous damage due to fires and loss of equipment. But of far greater importance is the danger to human life through electrocution. Ground faults in particular pose the risk of death because a human is generally at ground potential, thereby providing an alternate current path. It takes only about 5 mA to cause a shock, and as …

Another Test for Lightning Protection

Jeffrey R. Jowett Columns, Fall 2019 Columns, Tech Tips

It doesn’t take an electrician or engineer to know that lightning is a major cause of electrical interference and damage. Protecting the electrical system against such a danger is paramount. A lightning stroke can be hotter than the surface of the sun, with voltage estimated as high as 120 million volts, including 400 kA and 500 megajoules of energy. Utility …

10 Design Features for Electrical Safety

Jeffrey R. Jowett Columns, Summer 2019 Columns, Tech Tips

The National Fire Protection Association (NFPA®) revised its NFPA 70E, Standard for Electrical Safety in the Workplace in 2018 “to assist OSHA in preparing an electrical safety standard that would serve OSHA’s needs and that could be expeditiously promulgated through the provisions of…the Occupational Safety and Health Act.” Responsible electrical test instrumentation manufacturers accept 70E as a valuable guideline as …

Computer-Based Technology for Ground Testing

Jeffrey R. Jowett Columns, Spring 2019 Columns, Tech Tips

Since its inception in the early 20th century, testing grounded electrodes has been grounded on one technique and technology only: Fall of Potential. The test instrument made contact with the earth through long leads and driven probes, injected a current between the electrode being tested and a remote probe, and measured the voltage drop caused by earth resistance to another …