Grounding is not just for lightning protection

9 July 2013

When we hear the word ‘grounding’ we typically think lightning. But grounding is used for many things in many situations, not just to prevent us from getting struck by lightning.

When it comes to ground testing, installation and maintenance, grounding becomes particularly important to guard against electrical disturbances over a wide range of sources. Relatively massive currents and voltages may be associated with breakdowns, short circuits and ground faults; however, milliamp and millivolt levels can be all it takes for noise, harmonics or leakage to take an electrical system out of service.So why not protect against all these potential pitfalls?

The best way to protect oneself and/or the expensive equipment that can be taken out by a buildup of voltages is to follow the National Electrical Code.This code defines ‘effectively grounded’ as intentionally connected to earth through a ground connection or connections of sufficiently low impedance and having sufficient current-carrying capacity to prevent the buildup of voltages that may result in undue hazards to connected equipment or persons.

Proper grounding ties the electrical system to the earth.This fixes voltage ratings of electrical equipment, limits stress on insulation within rated tolerances to reduce the rate of risk to individuals as well as provides a relatively stable system with minimum transient over-voltages and facilitates quick isolation of ground faults.

There are many different types of ground testers to choose from depending on the application or other factors.A four-terminal model is a must for testing conductivity of the soil itself, whereas a three-terminal model is used for installation or maintenance testing.It can be useful to have extra digits on display for improved accuracy and resolution for both types of measurements.A fourth terminal can come in handy if the small amount of lead resistance must be eliminated in order to make especially low resistance measurements.

So the next time equipment in your electrical system is being serviced, first check to make sure proper grounding is in place. Then test the ground to ensure it’s suited to the task and can properly prevent voltage buildup in your system.