Key Takeaway
A visible-break disconnect switch is a switch-disconnector whose contact position is physically observable through a viewing window or mechanical indicator, allowing visual confirmation that the circuit is truly de-energized. It is mandatory in high-risk installations (industrial sites, public buildings, hospitals, power plants), fire safety systems, high-maintenance installations, and wherever NF C 15-100 or local regulations require visual verification of the disconnection state. Socomec offers the SIRCO MV range (100 A to 160 A, 3P or 4P) available at Optim-Elec.
What Is a Visible-Break Disconnect Switch?
A visible-break disconnect switch (also called a visible-break switch-disconnector) is a disconnection device that provides direct visual confirmation of its contact state (open or closed). This visualization takes two forms:
- Viewing window: a transparent window on the front of the device allows direct observation of the moving contacts (open = visible separation of contacts).
- Mechanically-linked position indicator: a position indicator directly coupled mechanically to the contacts (not to the operating handle), ensuring the indication reflects the actual contact state.
Why Is Visible Break Important?
Visible break addresses a fundamental personnel safety concern during maintenance and lockout/tagout operations:
1Eliminating Doubt
A standard disconnector indicates its position through the operating handle, but an internal mechanical fault could leave the contacts closed while the handle is in the open position. The visible-break disconnector eliminates this risk by allowing direct verification of the contact state.
2Compliance with Lockout/Tagout Procedures
Lockout/tagout procedures (NF C 18-510) require verification of effective circuit separation before any work. The visible-break disconnector facilitates this step by providing immediate visual proof of disconnection.
3Regulatory Requirement for Specific Installations
The NF C 15-100 standard and specific regulations (public buildings, classified installations) may mandate the use of a visible-break disconnector for certain circuits or applications. This applies particularly at the head of switchboards, on safety circuits, and in premises with fire or explosion risks.
When to Use a Visible-Break Disconnect Switch
| Application | Why Visible Break | Regulatory Reference |
|---|---|---|
| High fire-risk industrial sites | Visual confirmation of de-energization before work in a hazardous environment | NF C 15-100, ICPE |
| Public buildings (hospitals, airports, retail) | Occupant safety — identifiable and verifiable general disconnection required | French ERP regulations, NF C 15-100 |
| Power plants and transformer substations | Reliable isolation of high-power circuits before maintenance | NF C 13-100, NF C 13-200 |
| Fire safety systems (SSI) | Verification of safety equipment power supply status | NF S 61-970 |
| High-maintenance installations | Frequent interventions — fast and reliable work zone securing | NF C 18-510 |
| MLVS and industrial switchboards | Switchboard head disconnection with visual confirmation for lockout | NF C 15-100, IEC 60947-3 |
Difference from a Standard Disconnect Switch
| Criterion | Standard Disconnector | Visible-Break Disconnector |
|---|---|---|
| Position indication | By operating handle only | By direct viewing of contacts or mechanically-linked indicator |
| Indication reliability | Risk of handle/contact discrepancy if mechanical fault | Indication reflects actual contact state — maximum reliability |
| Lockout compliance | Requires additional voltage absence verification | Direct viewing provides visual proof (voltage testing still recommended) |
| Cost | Lower | Slightly higher (viewing window or indication mechanism) |
| Applications | Standard installations, residential | Critical sites, industrial, public buildings, high maintenance |
⚠️ Safety Reminder
Even with a visible-break disconnector, voltage absence verification with an approved tester remains a recommended step in the lockout/tagout procedure. Visible break is an additional safety level, not a substitute for voltage testing.
The Socomec SIRCO MV Range
Optim-Elec distributes visible-break switch-disconnectors from the Socomec SIRCO MV range, designed for modular switchboard mounting:
| Reference | Current | Poles | Mounting |
|---|---|---|---|
| 22003110 | 100 A | 3P | Modular DIN rail |
| 22004110 | 100 A | 4P | Modular DIN rail |
| 22003012 | 125 A | 3P | Modular DIN rail |
| 22004012 | 125 A | 4P | Modular DIN rail |
| 22003016 | 160 A | 3P | Modular DIN rail |
| 22004016 | 160 A | 4P | Modular DIN rail |
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Frequently Asked Questions — Visible-Break Disconnect Switch
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Key Takeaways
- A visible-break disconnector allows visual verification that the contacts are physically open (viewing window or mechanical indicator).
- It eliminates doubt about the actual circuit state — higher safety level than a standard disconnector.
- Mandatory or recommended for: industrial sites, public buildings, power plants, fire safety systems, MLVS, high-maintenance installations.
- Visible break facilitates lockout/tagout but does not replace voltage absence verification.
- The Socomec SIRCO MV range offers modular visible-break disconnectors from 100 A to 160 A in 3P or 4P.
- The additional cost is minimal compared to the safety benefit of visual disconnection confirmation.
