Introduction
As an electrician working on commercial buildings, I occasionally come across unusual electrical grounding issues that require some extra troubleshooting. Proper grounding is essential for safety and for equipment to function properly. Faulty or insufficient grounding can lead to shock hazards, equipment damage, and poor power quality. In this article, I will share my experience and tips for troubleshooting unusual grounding problems in commercial settings.
Common Causes of Unusual Grounding Issues
There are a few key factors that can lead to atypical grounding situations:
Older Electrical Systems
Many older buildings have outdated electrical systems that were installed before current grounding codes and standards were in place. Often, the grounding measures are inadequate or have degraded over time.
Incompatible Mix of Electrical Systems
It's common for commercial spaces to have an incompatible mixture of old and new electrical systems cobbled together over time as upgrades are made. This mismatch can create grounding discontinuities.
Use of Improper Grounding Procedures
In some cases, previous electricians may have used improper grounding methods against code requirements, leading to problems down the road.
Faulty Main Bonding Jumper
Issues with the main bonding jumper between the neutral and ground at the main service panel can lead to voltage on the grounding system throughout a building.
Corroded Grounding Electrodes
Over time, ground rods, water pipes, or concrete encased electrodes can become heavily corroded, damaging their effectiveness as grounding electrodes.
Signs of Abnormal Grounding Issues
Some of the typical indicators that unusual grounding problems may be present include:
- Tingling sensation or small shocks from touching appliances
- Measuring voltage between neutral and ground on circuits
- GFCIs or AFCIs tripping without an apparent cause
- Electronic equipment malfunctioning inexplicably
- Measureable stray currents on grounding conductors
If I come across any of these symptoms, it prompts me to do further testing to isolate the root cause.
Steps for Diagnosing Problems
When troubleshooting tricky grounding issues in commercial buildings, I take a systematic approach:
Inspect and Verify Main Grounding Electrode System
- Check for damage to ground rods and bonding connections
- Verify proper clamping and continuity
- Look for corrosion on electrodes and conductors
Test for Voltage Between Neutral and Ground
- This voltage should read close to zero on properly grounded systems
- Any significant voltage indicates an issue with neutral-to-ground bonding
Evaluate Grounding Electrode Resistance
- Use a ground resistance tester to measure resistance to earth
- Compare readings to IEEE guidelines for maximum allowed resistance
Check for Shared Neutral Issues
- Shut off individual circuits and retest neutral-to-ground voltage to check for a shared neutral problem
Inspect Equipotential Bonding
- Verify bonds between grounding electrodes and metal building systems like rebar and plumbing
- Check continuity of bonding jumpers and tightness of connections
Consider Stray Currents
- Use a clamp meter to measure current on grounding electrode conductors and bonding jumpers
- Helps identify any stray currents from other equipment flowing on the grounding system
By methodically working through these test procedures, I can usually get to the bottom of atypical grounding issues.
Solutions for Faulty Grounding
Once I've identified the cause of abnormal grounding, there are several ways I can restore proper functioning:
- Install new ground rods or grounding electrode system if corrosion is too severe
- Replace faulty main bonding jumper in service panel if neutral-to-ground voltage is high
- Rewire to meet current grounding code requirements if old system is inadequate
- Install isolation transformers or GFCI protection in certain cases to work around grounding problems temporarily
- Remove shared neutral conditions by separating neutral conductors
- Fix open grounding electrodes or loose connections
- Reroute wiring and cabling to avoid induced stray currents
In many cases, upgrading to a modern grounding system per NEC and IEEE guidelines is the best long-term solution.
Key Takeaways
Troubleshooting unusual grounding issues in commercial buildings requires patience and a systematic approach, but can be solved with persistence. The keys I've learned are:
- Understand common causes like old electrical systems and incompatibilities
- Recognize symptoms like shocks, malfunctioning equipment, and tripped GFCIs
- Methodically test grounding electrodes, bonding, voltages, and continuity
- Consider stray currents from other equipment as a possibility
- Make repairs and upgrades to meet modern grounding code requirements
No two grounding problems are exactly alike, but with the right knowledge and methodical troubleshooting, even tricky grounding issues can be solved for safe and robust electrical systems. Let me know if you have any other questions!