Tuesday: The Hidden Danger of Dual-Source Equipment
Locking out the AC side does not de-energize the DC side. Here's why.
The Core Issue: Most LOTO (Lockout/Tagout) training focuses on single-point AC supply breakers. However, equipment like forklift chargers or solar inverters often have secondary power sources (like battery banks or PV arrays).
The Lesson: Locking out the AC side does not de-energize the DC side. Semiconductors and internal busses can remain fully energized.
Actionable Takeaway: Always consult the specific equipment schematic and check for stored energy or secondary sources before declaring a zero-energy state.
See also our incident RCA on the forklift charger near-miss.
Post Conclusion
Failure Mode — Do Not Ignore This post describes a failure mode or active hazard. Do not ignore the warning signs described.