ZB4-BZ101
ActiveHarmony XB4 1NO Contact Block
Single contact block with 1 normally open (NO) contact for Schneider Harmony XB4 series. Screw clamp terminals.
Common Applications
Contact block that snaps onto the rear of any Schneider Harmony XB4 button head. The 1NO (Normally Open) contact closes the circuit when the button is pressed — standard for start, enable, and acknowledge functions. Rated for 6A at 120VAC, 10 million mechanical operations. When replacing a worn button, check the contact block first — if the button works intermittently, the contact block is usually the failed part, not the button head. One of the most-replaced components in industrial maintenance.
Commonly Found On
Compatibility
Fits all Schneider Harmony XB4 and XB5 button heads. Also fits legacy Telemecanique XB2 mounting. The ZBE-101 (element without base) stacks on top for dual-contact configurations. Not compatible with Eaton M22, ABB MP, or Siemens 3SU1 — those use their own contact blocks.
Specifications
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Certifications
Third-party safety certifications. UL = required for US NEC installations. CE = EU compliance. CSA = Canadian standards.
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UL, CSA, CE
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Contact Configuration
Normally Open — circuit is off until you press. Standard for start/go/enable functions.
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1NO
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Current rating
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10A
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Terminal Type
How you connect wires. Screw clamp is most common in industrial. Spring cage is faster but requires proper ferrules.
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Screw Clamp
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Max Voltage
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600V
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Specs with this icon are linked to the manufacturer's original source page
You'll Also Need
This is a modular component. For a complete assembly, you may also need:
Compatible Alternatives
These products are functionally equivalent cross-references from other manufacturers.
Installation Quick Reference
Mounting: Snap onto the rear of any compatible button body in the same series. The latch clicks audibly when properly seated. Some models require a mounting adapter.
Wiring: Terminals are marked NO (11/12) or NC (21/22). Use 0.5-2.5mm² wire with ferrules. Tighten to 0.8 Nm. Verify with a multimeter before energizing.
Dimensions
Wiring Diagram
Troubleshooting
Intermittent switching
Silver contacts are pitted from arcing. Replace the contact block — they are consumable parts. If arcing is severe, check that the switched load doesn't exceed the contact rating (typically 6A at 120VAC).
Contact block won't snap onto button body
Verify the contact block series matches the button head series (e.g., Schneider ZB4 blocks fit ZB4 heads only, not ZB5). Check for debris or damage on the mounting tabs.
Where to Buy
Price range
$1.64 — $19.64
across 4 distributors
Quick Specs
- Certifications
- UL, CSA, CE
- Contact Configuration
- 1NO
- Current rating
- 10A
- Terminal Type
- Screw Clamp
- Max Voltage
- 600V
What People Are Saying
“9 times out of 10 it is the contact block, not the button head. The silver contacts pit over time from arcing. Replace the ZB4-BZ101 (about $5) before replacing the whole assembly ($25+). Save yourself the trouble.”
“We schedule contact block replacements every 2 years on our high-cycle machines. The Schneider ZB4-BZ101 blocks are rated for 10M cycles but in a stamping press application they see that in about 18 months. Cheap insurance against nuisance faults.”
Learn More
Data Sources
Specifications and product data sourced from the following references.
