Elevator Safety Systems | Episode 7
Terminal Limit Switches
Three Layers of Electrical Protection
When discussing elevator safety, most engineers immediately think about the Governor, Safety Gear, or Buffers. However, another critical safety system works silently at both ends of the hoistway—the Terminal Limit Switches.
Modern elevators typically use three independent electrical protection levels at both the top and bottom of the shaft:
🔹 Normal Terminal Limit Switch – Stops the elevator if it exceeds its normal stopping position.
🟡 Overtravel (Up/Down) Limit Switch – Provides an additional protection layer if the car continues beyond the normal terminal limit.
🔴 Final Limit Switch – The last electrical safety device. It disconnects the driving power before the elevator reaches the mechanical end of travel.
This layered safety philosophy ensures that multiple independent protection levels are available before the car reaches the buffers, significantly enhancing passenger safety and protecting the elevator equipment.
These protective devices are part of the overall safety concept defined by EN 81-20, while their performance and testing requirements are covered by EN 81-50.
Because in elevator engineering, safety is never achieved by a single device—it’s achieved by multiple independent layers working together.
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