“Troubleshooting Unusual Electrical Grounding Issues in Older Commercial Buildings”

Troubleshooting Unusual Electrical Grounding Issues in Older Commercial Buildings

As an electrician working on older commercial buildings, I occasionally come across unusual electrical grounding issues that require some troubleshooting to resolve. Here is an in-depth look at some of the common causes and solutions for these types of problems:

Typical Causes of Unusual Grounding Issues

There are a few key factors that can lead to atypical grounding problems in older commercial buildings:

Age and Deterioration of Electrical Systems

Multiple Additions and Renovations

Use of Metal Piping for Grounding

Lack of Proper Grounding Design

Typical Unusual Grounding Problems

Some specific unusual grounding issues that can stem from the above causes include:

Ground Potential Voltage Differences

System Grounding But No Equipment Grounding

Intermittent Ground Faults

Unusual Voltages on Equipment Cases

Tingle Voltages

Tips for Troubleshooting the Issues

When unusual grounding issues are suspected, there are some good troubleshooting techniques to employ:

In many cases, resolving odd grounding problems in old buildings requires creating a proper grounding electrode system where none exists. That may mean driving new ground rods, establishing new bonding connections, and replacing deteriorated wiring. Reworking the grounding can be labor-intensive but helps avoid many dangers.

Case Example: Tracing Tingle Voltage in a Hospital

I once worked on fixing unusual grounding issues in an old hospital. Users were experiencing tingle voltages on metal surfaces like sinks and cabinets. Using a multimeter, I found higher than normal voltages on those grounded objects.

Examining the blueprints showed that two wings of the hospital, built decades apart, had separate grounding electrode systems. I inspected the main panel and found no bond between the two. Installing proper bonding between the systems and adding new ground rods for good measure solved the issue and eliminated the tingle voltages patients and staff had felt.

Key Takeaways