Siemens 3SU1400-1AA10-1CA0 — NC Contact Block Buyer Review

By Abdullah Zahid
12 min read
Siemens 3SU1400-1AA10-1CA0 normally closed contact module with screw terminals for SIRIUS ACT 3SU1 push-button assemblies

Siemens 3SU1400-1AA10-1CA0 Contact Module with 1 Contact Element, 1 NC, Screw Terminal, Front Plate Mounting — Specs, Price, and Alternative Contact Blocks

If you are specifying or replacing a normally closed contact block in a SIRIUS ACT 3SU1 push-button assembly, the Siemens 3SU1400-1AA10-1CA0 is the standard field-replaceable module engineers reach for. Rated at 10A continuous and 500V AC/DC, with screw terminals and a positive opening mechanism that satisfies IEC 60947-5-1 requirements, this single-channel NC contact module covers the majority of safety interlock and control circuit applications on the industrial floor. The decision usually comes down to one question: is this the right contact configuration and current rating for your circuit — or do you need a different variant from the SIRIUS ACT family?

If you have already confirmed this is the correct part for your application, check current pricing and availability for the Siemens 3SU1400-1AA10-1CA0 at LeadTime.ca — ships worldwide.

Who Should Buy the Siemens 3SU1400-1AA10-1CA0 — and Who Should Not

This contact module is the right choice when your application meets all of the following criteria:

  • Your circuit requires a normally closed (NC) contact configuration — contacts closed at rest, opening when the button is actuated
  • Rated voltage does not exceed 500V AC or 500V DC
  • Continuous current draw does not exceed 10A
  • Screw terminal connection is acceptable for your installation method or retrofit scenario
  • Front-plate mounting is required — rear-mount configurations require a different housing
  • Your existing control station is part of the SIRIUS ACT 3SU1 series

If your application requires spring-type terminals for faster OEM assembly, higher current capacity beyond 10A, or a normally open configuration, this is not the correct variant. See the comparison table below for the 3SU1400-1AA10-1CA1 (spring terminal), 3SU1400-1AA10-3CA0 (20A), and 3SU1400-1AA10-1FA0 (NO) alternatives.

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What the Siemens 3SU1400-1AA10-1CA0 Actually Does in a Control Circuit

The 3SU1400-1AA10-1CA0 is a Contact Module with 1 Contact Element, 1 NC, Screw Terminal, Front Plate Mounting — part of the SIRIUS ACT 3SU1 series. Its role is straightforward: it provides a single-channel, normally closed switching contact that integrates into the back of a SIRIUS ACT push-button or indicator light assembly mounted in a control station front panel. When the button is not actuated, the contact is closed and current flows. When the button is pressed, the contact opens and the circuit breaks.

What distinguishes this module from a generic contact block is the positive opening mechanism. Rather than relying on spring force alone to separate contacts, the positive opening design physically drives the contacts apart when the actuator is pressed. This is not a marketing claim — it is a functional requirement under IEC 60947-5-1 for emergency stop circuits and safety-interlock applications. In pharmaceutical, automotive, food processing, and machine guarding applications, this mechanism is the baseline requirement for any NC contact in a safety loop. SIRIUS ACT contact modules are rated for 10 million switching cycles mechanical life, which in three-shift production environments translates to years of reliable service before replacement is needed.

The screw terminal design accepts wire sizes in the 1.5 to 2.5 mm² range (10–14 AWG typical), allowing field technicians to replace a failed module and reconnect field wiring without soldering, crimping tools, or removing the entire control station. This reduces mean time to repair in emergency replacement scenarios significantly, which is why MRO procurement departments standardize on SIRIUS ACT modules across multi-site facilities.

Where This Contact Module Sits in Your System Architecture

The 3SU1400-1AA10-1CA0 sits at the field device level — between the operator interface (push-button actuator) and the control logic input or safety relay that interprets the switching signal. It is the electrical element that does the actual switching work inside the mechanical housing of the push-button station.

  • PLC or safety relay receives switching signal from this contact module via hardwired control circuit
  • Control cabinet terminal block distributes wiring from field devices to the contact module screw terminals
  • SIRIUS ACT 3SU1 push-button actuator (front-panel mounted) mechanically drives the contact module when pressed
  • The 3SU1400-1AA10-1CA0 contact module provides the NC switching element inside the actuator housing
  • Downstream: solenoid valve, motor starter coil, or safety relay input that responds to the open/closed state of the NC contact

Which Industries and Machine Types Use This Contact Block

The 3SU1400-1AA10-1CA0 appears across a wide range of industrial control applications wherever a hardwired NC contact in a front-panel push-button station is required. In heavy manufacturing and automotive assembly, it is the standard contact element behind emergency stop buttons and machine guarding interlocks where positive opening is mandatory. In food and beverage processing and pharmaceutical manufacturing, the IEC 60947-5-1 certification satisfies regulatory requirements for safety-critical switching without additional engineering validation.

Packaging machinery OEMs standardize on SIRIUS ACT contact modules during control cabinet design because the modular architecture allows parallel contact modules to be stacked on a single actuation point, supporting multi-channel safety circuit configurations without adding new push-button holes to the panel. Water treatment and pulp and paper facilities use this module for MRO replacement stock, keeping spares on hand to minimize downtime when a contact fails in a remote pump station or motor control center.

In retrofit applications, the front-plate mounting and screw-terminal design make this module compatible with existing SIRIUS ACT installations regardless of installation age, provided the push-button actuator is from the 3SU1 series.

Application Typical Deployment
Emergency stop circuits NC contact in hardwired safety loop; positive opening mandatory per EN 60204-1
Machine guarding interlocks Front-panel push-button station on production cell; contact feeds safety relay input
MRO replacement on production lines Direct swap for failed contact block in existing SIRIUS ACT 3SU1 assembly
OEM control cabinet integration Multi-contact configuration stacked on single push-button actuator for parallel safety inputs
Retrofit of legacy control panels Modernization of older push-button stations with current SIRIUS ACT standard modules
Pharmaceutical and food processing IEC 60947-5-1 certified NC contact for regulatory-compliant safety-interlock circuits

Specifications Every Engineer Needs Before Ordering

Parameter Value
Contact Type SPST-NC (Single Pole Single Throw, Normally Closed)
Rated Current 10A continuous
Rated Voltage AC 500V
Rated Voltage DC 500V
Insulation Voltage 500V
Contact Protection Degree IP40 (component) / IP20 (terminal area)
Mechanical Service Life 10 × 10⁶ switching cycles
Terminal Type Screw terminal, single entry per contact
Operating Temperature -25°C to +70°C (storage: -40°C to +80°C)
Compliance Standards IEC 60947-1, IEC 60947-5-1, RoHS 2

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

3SU1400-1AA10-1CA0 vs. Other SIRIUS ACT Contact Module Variants — Which One Do You Actually Need?

The suffix structure of the SIRIUS ACT 3SU1400 family carries all the information you need to select the correct variant. The -1CA0 ending identifies this as a normally closed (NC) contact with screw terminals. Changing a single character in the suffix changes contact type, current rating, or terminal type — which is why wrong-part orders in this family are common. Use the table below to confirm your selection before placing a purchase order.

Model Contact Type Current Voltage Terminal Use Case
3SU1400-1AA10-1CA0 NC (normally closed) 10A 500V AC/DC Screw Standard safety interlock, normally closed logic
3SU1400-1AA10-1FA0 NO (normally open) 10A 500V AC/DC Screw Normally open logic, inverse application
3SU1400-1AA10-3CA0 NC (normally closed) 20A 500V AC/DC Screw Higher-current loads, motor circuits
3SU1400-1AA10-4CA0 NC (normally closed) 40A 500V AC/DC Screw High-current industrial applications
3SU1400-1AA10-1CA1 NC (normally closed) 10A 500V AC/DC Spring OEM assembly, faster installation

If your circuit requires NC configuration at 10A with screw terminals, the 3SU1400-1AA10-1CA0 is the correct choice — check current stock and pricing at LeadTime.ca.

Expert Verdict: Is This the Right Contact Module for Your Project?

The Siemens 3SU1400-1AA10-1CA0 is a well-specified, field-proven contact module that delivers exactly what it promises: a single NC switching contact, rated for 10A continuous at 500V AC/DC, with positive opening action and screw terminals, in a modular form factor that drops into any SIRIUS ACT 3SU1 front-panel push-button station. For emergency stop circuits, safety-interlock applications, and MRO replacement scenarios in existing SIRIUS ACT installations, this module is the straightforward choice. The IEC 60947-5-1 compliance and positive opening mechanism are genuine functional differentiators for safety-critical circuits, not just label claims. At a mechanical life rating of 10 million switching cycles, the module holds up in high-cycle production environments without requiring frequent replacement as part of a preventive maintenance schedule.

Where this module has real limits: if your circuit draws more than 10A continuous, this is the wrong part — specify the 3SU1400-1AA10-3CA0 at 20A or 3SU1400-1AA10-4CA0 at 40A instead and do not assume a 20% de-rating will cover a borderline application. If your assembly process favors push-in spring terminals for speed, the 3SU1400-1AA10-1CA1 is the identical module with that connection type. And if your logic requires a normally open contact, the -1CA0 suffix will invert your circuit — the 3SU1400-1AA10-1FA0 is the NO equivalent at the same current and voltage ratings.

From a procurement standpoint, this is an active, stocked part in the SIRIUS ACT family. Minimum order quantity is typically 5 units, which aligns with most MRO restocking and panel build scenarios. Lead times typically run 2 to 4 weeks from major distributors, though stock positions vary. For emergency replacement situations, volume availability, or multi-SKU orders spanning the SIRIUS ACT family, it is worth confirming stock before committing to a build schedule. If this matches your system requirements, view current stock and pricing for the 3SU1400-1AA10-1CA0 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 for the 3SU1400-1AA10-1CA0

  • Always apply lock-out/tag-out before beginning installation or replacement; verify circuit isolation with a multimeter before touching terminals
  • Strip 8–10mm of insulation from field wires sized 1.5 to 2.5 mm² (10–14 AWG typical); insert into screw terminal openings and tighten hand-tight — do not use power tools on screw terminals
  • Slide the module into the SIRIUS ACT 3SU1 guide rails and engage the friction-lock screw until snug; verify the module is fully seated before powering the circuit
  • After installation, perform a continuity test: the NC contact should show continuity between the C and NC terminals at rest, and open when the button is actuated
  • For safety-circuit applications, verify the complete system meets the SIL or PL requirements of your application — this module provides positive opening action per IEC 60947-5-1 but full system safety rating must be evaluated at the system level per ISO 13849-1 and EN 60204-1

Full wiring diagrams and installation procedures are available in the Siemens SIRIUS ACT 3SU1 product documentation at sieportal.siemens.com.

What Engineers Get Wrong When Ordering This Part

Wrong-part orders in the SIRIUS ACT 3SU1400 family almost always come down to one of three errors: contact type inversion (NC vs. NO), underestimating current draw, or specifying the wrong terminal type for the assembly process. Use this checklist before finalizing any purchase order for the 3SU1400-1AA10-1CA0:

  1. Verify contact type is NC (normally closed), not NO (normally open). Check final digit sequence: -1CA0 indicates NC.
  2. Confirm voltage requirement does not exceed 500V AC or 500V DC. If higher voltage needed, this module is not suitable.
  3. Confirm application current draw does not exceed 10A continuous. Higher-current applications require alternative modules.
  4. Verify screw terminals are acceptable connection method. If spring terminals or solder pins required, order different variant.
  5. Confirm front-plate mounting method matches your control station. Rear-mounting requires different housing.
  6. Check minimum order quantity (MOQ typically 5 units) aligns with procurement strategy.
  7. Verify SIRIUS ACT 3SU1 series compatibility with your existing push-button and indicator light models.
  8. Confirm positive opening requirement is mandatory for your safety-rated circuit. If not safety-critical, verify no over-specification.

If any item on this checklist raises a question before you order, contact the LeadTime.ca team — we can confirm the correct variant for your application before the purchase order is placed.

Frequently Asked Questions

How do I confirm whether my existing contact block is NC or NO before ordering a replacement?

Use a multimeter set to continuity mode. With the push button in its normal (not actuated) state, probe the C and NC terminals. If you get continuity at rest, the contact is NC and the 3SU1400-1AA10-1CA0 is the correct replacement. If there is no continuity at rest, the existing block is NO and you need the 3SU1400-1AA10-1FA0 instead. Always verify with the circuit schematic as well — do not rely on physical testing alone for safety-circuit replacements.

Is the 10A current rating sufficient for a motor starter control circuit?

For the pilot control circuit (coil supply circuit) of a motor starter, 10A is generally sufficient, as motor contactor coil currents are typically well below this threshold. However, if the contact block is switching the motor load directly rather than a control circuit, the 10A rating will almost certainly be exceeded. In that case, specify the 3SU1400-1AA10-3CA0 at 20A or 3SU1400-1AA10-4CA0 at 40A. Always calculate peak inrush current, not just steady-state draw, and build in margin below the 10A limit.

What is the minimum order quantity, and can I buy a single unit for an emergency replacement?

The minimum order quantity for the 3SU1400-1AA10-1CA0 is typically 5 units as a standard procurement quantity for the SIRIUS ACT series. In emergency replacement scenarios, availability of smaller quantities depends on distributor stock and policy. Contact the LeadTime.ca team directly to confirm what is available for immediate shipment — expedited handling options may be available for urgent production downtime situations.

Can I stack multiple 3SU1400-1AA10-1CA0 modules on a single push-button actuator for a dual-channel safety circuit?

Yes, the SIRIUS ACT 3SU1 modular architecture supports stacking multiple contact modules on a single actuator, which is a standard approach for dual-channel safety inputs. Confirm the physical module holder and actuator you are using supports the number of contact modules required — the SIRIUS ACT product configurator on sieportal.siemens.com can be used to validate multi-module assembly configurations before ordering.

Does the 3SU1400-1AA10-1CA0 satisfy IEC 60947-5-1 requirements for emergency stop applications on its own?

The module itself is certified to IEC 60947-5-1 and incorporates the positive opening mechanism that standard requires for NC contacts in emergency stop circuits. However, achieving a full system safety rating (such as ISO 13849-1 PLd or IEC 61508 SIL2) requires evaluation of the complete safety function — including the actuator, wiring, and safety relay or controller. The 3SU1400-1AA10-1CA0 provides the contact element component of that system; overall SIL or PL validation is a system-level determination.

What is the typical lead time, and does LeadTime.ca ship internationally?

Standard lead time for the 3SU1400-1AA10-1CA0 is typically 2 to 4 weeks from major distributors, though stock positions vary. LeadTime.ca ships worldwide — if you are sourcing from outside North America or need to confirm availability before committing to a project schedule, contact the LeadTime.ca team for current lead time and shipping options for your region.

Why Order the 3SU1400-1AA10-1CA0 from LeadTime.ca

  • Ships worldwide — no geographic restriction on order fulfillment
  • Specializes in sourcing hard-to-find and low-MOQ industrial automation parts across the SIRIUS ACT family
  • Volume pricing available for multi-unit orders — contact directly for 10+, 25+, and 50+ unit pricing on the 3SU1400-1AA10-1CA0
  • Direct response from the LeadTime.ca team for lead time confirmation before you commit to a build or production schedule
  • Handles multi-SKU orders across SIRIUS ACT contact modules, push-button actuators, and indicator light assemblies in a single transaction

At-a-Glance Summary: Siemens 3SU1400-1AA10-1CA0

  • Contact Module with 1 Contact Element, 1 NC, Screw Terminal, Front Plate Mounting — part of the SIRIUS ACT 3SU1 series
  • Single-channel SPST-NC contact rated at 10A continuous, 500V AC/DC
  • Positive opening mechanism satisfies IEC 60947-5-1 requirements for emergency stop and safety-interlock circuits
  • Mechanical service life rated at 10 × 10⁶ switching cycles
  • Screw terminals accept 1.5 to 2.5 mm² (10–14 AWG) field wiring; no special tools required for replacement
  • Operating temperature range -25°C to +70°C; storage to -40°C to +80°C
  • IP40 protection on the component, IP20 at the terminal area
  • Certified to IEC 60947-1, IEC 60947-5-1; RoHS 2 compliant with no SVHC detected as of January 2024
  • Minimum order quantity typically 5 units; standard lead time 2 to 4 weeks
  • Key alternatives: 3SU1400-1AA10-1FA0 (NO), 3SU1400-1AA10-3CA0 (20A NC), 3SU1400-1AA10-1CA1 (spring terminal NC)