What It Is:

A Push-Pull Stop Switch is a manually operated control device used to start or stop equipment safely.
Push = Stop (emergency or routine shutdown)
Pull = Start (resume operation once safe)

Typical Applications:

1. Air Handling Units (AHU) – local start/stop
2. Exhaust & Supply Fans – maintenance safety
3. Chillers & Pumps – operator control during service
4. Industrial Equipment – quick emergency shutdown

Why It Matters in BMS:

These switches act as the local override control for field devices connected to your Building Management System.
Even if automation fails, the operator can ensure manual safety control right at the panel or equipment location.

Technical Insights:

Common sizes: 22mm / 30mm mounting
Contact Type: 1NO + 1NC (one normally open, one normally closed)
Action Type: Momentary or maintained
Material: Metal or heavy-duty plastic for industrial use
Often paired with indicator lamps for visual feedback

Pro Tip for Engineers:

When designing your BMS control panel, always label Push-Pull Stop switches clearly with color coding
🔴 Red = Stop
🟢 Green = Start
This ensures clarity, safety, and compliance with field standards.