In the early days of our control cabinet production, grounding was something we understood in theory, but we did not always consider it a top priority during assembly and commissioning.
That changed one day during the testing of a lift control cabinet.
While adjusting the electrical components, we occasionally felt a slight electric shock when touching the cabinet. It was not strong enough to cause injury, but it was clearly noticeable. At first, we suspected insulation damage or wiring mistakes. However, after careful inspection, we found that there was no actual electrical leakage.
The real cause turned out to be induced voltage.
Where Does the Induced Voltage Come From?
Modern lift control cabinets often contain components such as:
-
Variable Frequency Drives (VFDs)
-
DC power supplies
-
Switching power supplies
-
Motors and long motor cables
Even when these devices are operating normally, they can generate small amounts of induced voltage or leakage current due to electromagnetic coupling and internal filtering circuits.
If the cabinet paint coating is thin, scratched, or if certain metal parts are exposed, this small induced voltage may appear on the cabinet surface. Although the current is usually very small, touching the cabinet can create an unpleasant electric shock sensation.
This was exactly what happened during our testing.
The Bigger Problem: Electrical Interference
The slight electric shock was only the first symptom.
We later realized that induced voltage and poor grounding could create much more serious problems inside the control system.
Without proper grounding, electrical noise may interfere with:
-
PLC input and output signals
-
Relay operation
-
Limit switches and sensors
-
PLC status display screens
-
Communication signals
-
Variable frequency drive operation
Intermittent faults are often the most difficult problems to diagnose because they appear randomly and disappear without warning. In many cases, inadequate grounding can be one of the hidden causes.
Our Solution
After identifying the issue, we changed our control cabinet design.
A dedicated grounding terminal block was added inside every control cabinet.
The following components are connected to this grounding point:
-
Variable frequency drives
-
DC switching power supplies
-
Motor grounding wires
-
Cabinet doors and metal structures when necessary
The grounding terminal is then connected to a reliable external earth grounding point.
This simple improvement produced immediate results.
-
The electric shock sensation disappeared.
-
Electrical interference was significantly reduced.
-
PLC signals became more stable.
-
Display screens operated more reliably.
-
Overall system stability improved.
Lessons Learned
Grounding is often considered a small detail during electrical design, but in practice it can have a major impact on safety and reliability.
Even when there is no actual insulation failure, induced voltage and electromagnetic interference can still affect both operators and control systems.
For scissor lift platforms, hydraulic platforms, home lifts, and industrial machinery, proper grounding should never be treated as optional.
A good grounding system not only protects people, but also protects the entire control system.
Conclusion
Our experience taught us that some of the most valuable engineering lessons come directly from real-world troubleshooting.
Today, every control cabinet we build includes dedicated grounding terminals and a clear grounding layout.
The improvement costs very little, but the benefits in safety, reliability, and electrical stability are substantial.
Sometimes, the smallest wire inside a control cabinet can make the biggest difference.
If you have questions about our lift control systems or need technical support, please contact our engineering team — we are happy to help.
Related: IEC 60364 Electrical Installations Standard — the international benchmark for low-voltage electrical installation grounding requirements.
0 comments