Siemens 3su1050-1hb20-0aa0

By Abdullah Zahid
13 min read
Siemens 3SU1050-1HB20-0AA0 SIRIUS ACT 40mm red mushroom emergency stop pushbutton for industrial control panels

Siemens 3SU1050-1HB20-0AA0 EMERGENCY STOP Mushroom Pushbutton, 22 mm, Round, Metal, Shiny, Red, 40 mm, Positive Latching, acc. to EN ISO 13850, Rotate-to-Unlatch — Specifications, Selection Guide and Alternatives

When a controls engineer or procurement specialist searches for a Siemens emergency stop button with a 40 mm mushroom head, EN ISO 13850 compliance, and positive latching behavior, the 3SU1050-1HB20-0AA0 from the SIRIUS ACT family is typically the exact part they need. This 22 mm bezel, red shiny metal actuator delivers a 300,000-cycle mechanical service life, IP66/IP67/IP69K protection, and a rotate-to-unlatch reset mechanism — making it the standard reference design for washdown-heavy and safety-critical industrial environments worldwide. The decision usually comes down to confirming the mounting bezel size, the latching behavior, and whether the IP rating matches the installation environment before issuing a purchase order.

If you have already confirmed this is the right part, check current pricing and availability at LeadTime.ca — ships worldwide.

Who Should Buy the 3SU1050-1HB20-0AA0 — and Who Shouldn't

This button is the correct choice for engineers and buyers who meet all of the following criteria:

  • EN ISO 13850 emergency stop compliance is a hard requirement — non-negotiable for your OEM specification, safety audit, or facility standard
  • Your control panel uses a standard 22 mm mounting bezel cutout (22.3 mm actual diameter, tolerance +0.4 mm)
  • IP67 minimum ingress protection is required — washdown exposure in food, beverage, pharmaceutical, or chemical processing environments
  • Positive latching behavior is specified — the machine must stay de-energized until an operator deliberately twists the mushroom head to reset
  • 300,000-cycle mechanical service life is acceptable or exceeds your replacement interval requirements
  • Panel depth accommodates the 45.3 mm mounting height without interference from adjacent components or door closure

If your application requires a non-emergency latching function in amber, the 3SU1050-1HB20-0BA0 is the correct variant. If panel space is severely constrained and a 16 mm bezel form factor is required, evaluate the SIRIUS 16 mm series instead. If remote status indication or LED feedback is required at the button, an LED-integrated variant is the appropriate choice.

On this page:

What the 3SU1050-1HB20-0AA0 Actually Does in a Control System

The 3SU1050-1HB20-0AA0 is the actuator half of a two-part emergency stop assembly. The button itself — a 40 mm red shiny metal mushroom head mounted in a 22 mm round metal bezel — is the operator interface. When pressed, it activates a positive latching mechanism that locks the button in the depressed position and opens the associated contact block circuit, interrupting machine motion. The machine cannot restart until an operator physically grasps the mushroom head and rotates it to unlatch. This deliberate reset gesture is the core safety behavior mandated by EN ISO 13850, which prescribes that emergency stop devices must require a conscious, intentional action to return to the ready state — not a simple button release.

The button assembly itself carries no electrical contacts. It pairs with separately ordered Siemens SIRIUS contact block modules that plug into the rear of the 22 mm bezel housing. This modularity is a deliberate design feature of the SIRIUS ACT platform: if a contact block wears out after 300,000 cycles, you replace only the contact element, not the entire actuator. Conversely, if the mushroom head is physically damaged, the contact block is retained and only the actuator is replaced.

At 0.267 kg and with a snap-fit locking ring (no threading required), installation into a standard 22.3 mm panel cutout is straightforward. The 45.3 mm mounting height is the dimension most frequently overlooked in panel layout — verify panel depth and adjacent component clearances before mounting.

Typical System Architecture for a SIRIUS ACT Emergency Stop Installation

The 3SU1050-1HB20-0AA0 sits at the operator-interface layer of the safety circuit, between the control panel surface and the safety relay or safety PLC input that monitors machine state. Here is where it fits in a typical deployment:

  • Machine controller or safety PLC (upstream logic layer) — monitors the safety circuit state and commands motion control outputs
  • Safety relay or safety I/O module — monitors the normally-closed contact loop from the emergency stop contact block; detects open-circuit condition as stop command
  • 3SU1050-1HB20-0AA0 actuator paired with SIRIUS contact block module — the physical interface; operator presses to break the contact circuit
  • Control panel enclosure (NEMA 4 or 4X rated for washdown applications) — houses the button at operator-accessible height and orientation
  • Downstream machine motion devices (contactors, drives, servo amplifiers) — de-energized when the emergency stop contact opens the safety circuit

Industries and Applications Where This Button Is the Default Choice

Food and beverage processing facilities specify the 3SU1050-1HB20-0AA0 as a default emergency stop because the IP67 rating handles routine hose-down cleaning cycles without contact corrosion. The metal shiny construction resists the caustic cleaning agents common in dairy, meat processing, and beverage bottling lines in a way that plastic-bodied alternatives cannot.

Pharmaceutical and life sciences manufacturers select this button for the combination of EN ISO 13850 compliance documentation and the NEMA 4X rating, which covers corrosion resistance in environments where isopropyl alcohol and hydrogen peroxide cleaning are routine. The rotate-to-unlatch reset reduces the risk of accidental restart during clearance procedures, which matters in FDA-regulated environments where restart after an emergency stop must be a deliberate, documented action.

Automotive assembly and tier-one automotive suppliers standardize on SIRIUS ACT 22 mm buttons across production lines because the SIRIUS ecosystem means contact blocks, holders, and actuators are interchangeable. A single spare parts SKU covers dozens of machine types on the same floor, reducing inventory cost and eliminating compatibility errors during emergency maintenance.

Machine builders designing OEM equipment for global export specify this button because EN ISO 13850 is recognized in EU Machinery Directive compliance documentation and is referenced by OSHA and ANSI B11 standards in North America. One actuator covers the compliance requirement across most export destinations without redesign.

Application Typical Deployment
Food and beverage processing Hose-down rated emergency stop on conveyor control panels; IP67 required
Pharmaceutical manufacturing NEMA 4X enclosures with EN ISO 13850-compliant actuators for FDA-regulated lines
Automotive assembly Standardized SIRIUS ACT actuators across multi-machine production cells for spare parts commonality
Packaging machinery OEM 22 mm bezel emergency stop on export equipment requiring both EU and North American compliance documentation
Chemical processing NEMA 4X, IP69K-rated installations in corrosive or high-pressure washdown zones
Legacy system retrofit Direct replacement of worn 22 mm Siemens emergency stop buttons with identical contact block interface

Key Specifications: What Engineers Need Before Ordering

Specification Value
Mounting Bezel Diameter 22 mm (22.3 mm actual, tolerance +0.4 mm)
Mushroom Head Diameter 40 mm
Color and Material Red, shiny metal
Mounting Height 45.3 mm
Installation Width / Depth 40 mm wide / 26.3 mm deep
Protection Class IP66, IP67, IP69K
NEMA Enclosure Compatibility 1, 2, 3, 3R, 4, 4X, 12, 13
Operating Temperature -25 °C to +70 °C
Mechanical Service Life 300,000 cycles
Safety Standard EN ISO 13850; positive latching, rotate-to-unlatch

Full technical specifications are available on the product page at LeadTime.ca.

3SU1050-1HB20-0AA0 vs. SIRIUS ACT Variants — Which One Do You Actually Need?

Model Color Mechanism Intended Function When to Choose
3SU1050-1HB20-0AA0 Red, shiny metal Positive latching, rotate-to-unlatch Emergency STOP per EN ISO 13850 Safety-critical emergency stop; washdown environments; EN ISO 13850 compliance required
3SU1050-1HB20-0BA0 Amber/yellow, shiny metal Positive latching, rotate-to-unlatch Non-emergency latching stop function Facilities requiring latching buttons for functions other than emergency stop; color coding is mandated
3SU1050-1HA20-0AA0 Red, shiny metal Non-latching (spring return) Standard stop function without maintained state Non-safety-critical stop functions where spring return is acceptable; not for EN ISO 13850 emergency stop
SIRIUS ACT 16 mm series Various Varies by model Emergency or standard stop in compact panels Severely space-constrained panel layouts where 22 mm bezel does not fit; lower per-unit cost in high-volume builds

If your architecture requires a positive latching, rotate-to-unlatch emergency stop in a standard 22 mm bezel with EN ISO 13850 certification, the 3SU1050-1HB20-0AA0 is the correct choice — check current availability at LeadTime.ca.

Expert Verdict: Honest Assessment and Procurement Reality

The 3SU1050-1HB20-0AA0 does exactly what a safety-critical emergency stop actuator is supposed to do — and it does it with a level of build quality that justifies its position as the default specification on food, pharma, and automotive lines worldwide. The 40 mm red mushroom head is immediately recognizable to any operator who has worked on industrial machinery. The rotate-to-unlatch reset is intuitive enough that untrained personnel understand it on first contact, and deliberate enough that accidental restart during fault clearance is essentially eliminated. The IP67 rating, verified across IP66 and IP69K variants, means the button survives washdown cycles that destroy lesser actuators within months. At 300,000 cycles mechanical service life, a button used ten times per shift on a single-shift operation has a theoretical service life exceeding eighty years — in practice, environmental factors and physical damage drive replacement long before mechanical wear does.

Where this model has real limits: it is not the right choice if your facility requires a non-red color-coded latching button (use the 0BA0 amber variant), if your panel cutout is 16 mm rather than 22 mm, or if your safety system design requires LED status feedback at the button location. The button assembly carries no electronics and provides no remote status indication — if your safety PLC architecture requires confirmation that the button is in the reset-ready state before enabling a restart permissive, that logic must be handled at the contact block and controller level, not at the actuator. This is not a weakness of the 3SU1050-1HB20-0AA0 specifically — it is the correct design for a hardwired positive-opening safety device — but it is a real constraint that some modern safety architectures route around with electronic safety devices instead.

On the procurement side, the 3SU1050-1HB20-0AA0 is an active product with no discontinuation risk, and SIRIUS ACT 22 mm emergency stop variants are standard inventory at major industrial distributors globally. Lead times from same-day to two weeks depending on regional stock levels. Volume orders of 50 or more units typically qualify for pricing reductions. One important budgeting note: the button assembly is priced separately from the contact blocks that give it electrical switching capability — confirm your contact block part numbers and quantities before finalizing the purchase order. If you are replacing a failed button on an existing installation, the contact block is often still serviceable and does not need replacement. If you are specifying for a new machine build, budget for both components. If this matches your system requirements, view current stock and pricing at LeadTime.ca.

For volume pricing or to confirm lead time before committing to a build, contact the LeadTime.ca team directly — we ship worldwide.

Wiring and Installation Overview

  • The 3SU1050-1HB20-0AA0 actuator carries no electrical contacts — a separate SIRIUS contact block module must be ordered and mounted to the rear of the bezel housing before wiring; standard installations use one contact block, advanced safety loops may use two for higher SIL ratings
  • The mounting hole must be 22.3 mm diameter (tolerance +0.4 mm); the snap-fit locking ring secures the assembly without threading — verify panel thickness and material compatibility before insertion
  • Emergency stop contacts are typically wired normally-closed in series with the machine motion relay coil; button actuation opens the circuit and de-energizes all downstream motion — the circuit must be hardwired and must not be overridable by software control signals
  • Verify that the 45.3 mm mounting height clears all adjacent panel components, cable bundles, and door closure path before finalizing panel layout
  • After installation, perform a full functional test: press the mushroom head (audible click expected), confirm machine de-energization, then rotate to unlatch and verify restart permissive is restored — document the test result per your facility safety inspection procedure

Compatible Contact Modules and System Expansion

The 3SU1050-1HB20-0AA0 actuator is designed to work within the SIRIUS ACT 22 mm modular platform. The following component types are required or optional additions to complete a functional emergency stop assembly:

  • SIRIUS ACT contact block modules (3SU14xx series) — provide the electrical switching contacts; sold separately; available in normally-open, normally-closed, and dual-channel safety contact configurations for SIL 2-capable circuits
  • SIRIUS ACT holder / base modules — provide multi-contact configurations and mounting interfaces for complex panel layouts where more than one contact block is required
  • SIRIUS ACT front plate adapters — allow integration of the 22 mm button into multi-function operator panels or combined start/stop/emergency-stop assemblies
  • SIRIUS ACT protective collars — add mechanical guarding around the mushroom head to prevent accidental actuation in high-traffic or vibration-heavy environments

Wrong-Part Prevention Checklist: Eight Checks Before You Order

Run through every item on this checklist before placing your order. Returning or re-engineering around the wrong actuator costs far more than the time this takes.

  1. Verify button head diameter is 40 mm (not 22 mm, which is the bezel size) by measuring existing control panel opening
  2. Confirm red color is required (not amber, yellow, or green); check facility or OEM standards documentation
  3. Check that rotate-to-unlatch (reset) behavior is acceptable; some regions prefer automatic spring return
  4. Validate mounting height clearance (45.3 mm); ensure button does not interfere with adjacent controls or door closure
  5. Confirm IP67 protection class matches environment; IP69K required only for high-pressure spray washdown
  6. Verify positive latching design is required (prevents accidental restart); spring-return variants exist for different applications
  7. Check that NEMA 1, 2, 3, 4, or 4X rating matches enclosure protection level
  8. Confirm compatibility with existing control system: SIRIUS ACT buttons integrate via standard contact blocks (separate purchase)

If any item on this checklist raises a question before you order, contact the LeadTime.ca team — we can confirm the correct part number and verify availability before you commit.

Frequently Asked Questions

Does the 3SU1050-1HB20-0AA0 include the contact block, or does that need to be ordered separately?

The contact block is a separate order. The 3SU1050-1HB20-0AA0 is the actuator assembly only — the red 40 mm mushroom head and 22 mm metal bezel with positive latching mechanism. SIRIUS ACT contact block modules (3SU14xx series) must be specified and ordered independently. This modular design allows the contact block to be replaced independently if it reaches its electrical service life while the actuator remains serviceable, or vice versa.

Is IP67 sufficient for food processing washdown, or do I need IP69K?

IP67 covers immersion up to 1 metre and handles standard low-to-medium pressure hose-down cleaning in most food and beverage applications. IP69K is the correct rating for high-pressure, high-temperature spray washdown — common in meat processing, dairy, and heavy sanitation environments. The 3SU1050-1HB20-0AA0 is rated for both IP67 and IP69K; verify which protection class your facility washdown protocol requires before finalizing the specification.

What does the 300,000-cycle mechanical service life translate to in real production use?

At a maximum operating frequency of 600 cycles per hour, 300,000 cycles represents 500 hours of continuous actuation at maximum rate — far beyond any realistic emergency stop use pattern. In a typical production facility where the emergency stop is actuated a few times per shift for genuine stops plus routine testing, 300,000 cycles typically corresponds to 5 to 7 years of service life. High-cycle test environments or applications where the button doubles as a routine stop control will exhaust the mechanical life faster.

Can this button be used in place of a standard stop button, or is it only for emergency stop functions?

The 3SU1050-1HB20-0AA0 is specifically designed and certified for emergency stop duty per EN ISO 13850. Using it as a routine stop button is technically possible but wastes the safety-rated design and can create confusion if operators are conditioned to use the red mushroom button for routine stops. For standard stop functions without the positive latching emergency stop requirement, a non-latching variant (spring return) is more appropriate and typically lower cost.

What is the B10 value for this button, and how does it factor into SIL calculations?

The published B10 value for this button is 100,000 cycles at high demand rate. The proportion of dangerous failures is 20 percent for both low and high demand modes. The failure rate is 100 FIT at low demand rate per SN 31920. These values feed directly into your safety function reliability calculations for SIL 2 or SIL 3 emergency stop circuit designs — use them in conjunction with your safety relay or safety PLC documentation to calculate the overall PFH or PFD for the safety function.

Is the 3SU1050-1HB20-0AA0 compatible with legacy SIRIUS control systems installed 10+ years ago?

The SIRIUS ACT 22 mm platform maintains backward compatibility across the contact block interface, making the 3SU1050-1HB20-0AA0 a direct mechanical replacement for earlier SIRIUS 22 mm emergency stop actuators in most cases. Verify the contact block module part number on the existing installation before ordering — if the existing contact block is still serviceable, it may be reused with the new actuator, reducing replacement cost and installation time.

Why Order from LeadTime.ca

  • LeadTime.ca ships Siemens SIRIUS ACT components worldwide — no regional restrictions on ordering
  • Hard-to-source and short lead-time industrial parts are a core specialty; the team can confirm real-time stock before you commit to a build schedule
  • Volume pricing is available for orders of 50 or more units — contact the team directly to discuss project quantities
  • Both the actuator and compatible contact block modules are available through a single source, simplifying procurement for complete emergency stop assemblies
  • Fast response to quote requests — useful when emergency stop failure creates unplanned downtime and sourcing speed matters

At-a-Glance Summary

  • Model: Siemens 3SU1050-1HB20-0AA0 — SIRIUS ACT emergency stop mushroom pushbutton, 22 mm bezel, 40 mm red shiny metal head
  • Latching mechanism: Positive latching, rotate-to-unlatch reset — compliant with EN ISO 13850 emergency stop requirements
  • Protection class: IP66, IP67, and IP69K — suitable for standard washdown through high-pressure spray environments
  • NEMA compatibility: NEMA 1, 2, 3, 3R, 4, 4X, 12, 13 enclosures
  • Operating temperature range: -25 °C to +70 °C; storage range: -40 °C to +80 °C
  • Mechanical service life: 300,000 cycles at up to 600 cycles per hour maximum operating frequency
  • Mounting height: 45.3 mm — verify panel clearance before installation
  • Weight: 0.267 kg — button assembly only; contact blocks require separate order
  • Safety data: B10 value 100,000 cycles at high demand rate; 20% proportion of dangerous failures; 100 FIT failure rate at low demand rate
  • Primary industries: Food and beverage, pharmaceutical, automotive assembly, chemical processing, packaging machinery OEM