External Intumescent Accessory for Flush-Mounted Box Fire Sealing

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Solution Overview

Problem

Existing flush-mounted boxes with intumescent materials inside occupy valuable interior volume, reducing space for electrical equipment and wiring, and do not effectively meet fire-resistant standards.

Innovation Solution

The intumescent material is positioned outside the flush-mounted box, increasing the available interior volume by projecting through an unused opening, and the fire-resistant accessory is designed to accommodate electrical equipment and wiring while maintaining fire protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the intumescent material is placed inside the flush-mounted box, then the fire-resistant performance is achieved, but the interior volume available for electrical equipment and wiring is reduced

Engineering Contradiction:
Improvefire-resistant performanceVSAvoidinterior volume of flush-mounted box
Core Design Contradiction:
ReliabilityVSVolume of stationary object

Solution Approach 1:

The intumescent material is extracted from the interior of the flush-mounted box and repositioned to the exterior, where it is mounted on the back of the box. This extraction resolves the contradiction by removing the harmful occupation of interior space while preserving the fire-resistant function through the material's ability to expand and seal openings when exposed to heat.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The solution moves the intumescent material from a two-dimensional interior surface to a three-dimensional exterior position, utilizing the space behind and around the box rather than the constrained interior volume. This dimensional repositioning allows the material to perform its fire-sealing function without compromising the box's interior capacity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Volume of stationary object

If the intumescent material is positioned outside the flush-mounted box, then the interior volume is maximized, but the fire-resistant performance may be compromised

Engineering Contradiction:
Improveinterior volume of flush-mounted boxVSAvoidfire-resistant performance
Core Design Contradiction:
Volume of stationary objectVSReliability

Solution Approach 1:

The mounting structure acts as an intermediary between the intumescent material and the flush-mounted box, providing a secure attachment mechanism on the box's exterior. This intermediary ensures the material remains properly positioned to perform its fire-sealing function while allowing the box interior to remain fully accessible for electrical equipment and wiring.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If a conventional flush-mounted box is modified to be fire-resistant, then fire protection is achieved, but the complexity of the device increases

Engineering Contradiction:
Improvefire protectionVSAvoidcomplexity of flush-mounted box
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The fire-resistant functionality is segmented from the main box structure and implemented as a separate, attachable component. This segmentation allows the box itself to remain simple and unchanged, while the fire-protection function is added through a distinct module that can be independently installed and removed, thereby reducing overall device complexity.

Inventive Principle:
Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration maintains fire-resistant performance by obstructing flames and gases, while maximizing space for electrical components and wiring within the box.

Implementation Method 1

When the intumescent material is exposed to heat, it swells and then obstructs the box's sheath inlet openings, which expels air and prevents the passage of flames and gases through them

Methodology Applied
Scientific EffectIntumescent material expansion: Intumescent Materials

Data Source

PatentEP4556077A1Fire-protection accessory to be installed in a flush mounted box and fire-protection assembly comprising a flush mounted box and such a fire-protection accessory
Publication Date: 2025.05.21 LEGRAND FRANCE SA
  • EP4556077A1 patent drawingFigure 1~2
  • EP4556077A1 patent drawingFigure 3~4
  • EP4556077A1 patent drawingFigure 5

AI summary

The invention relates to a fire-resistant accessory (10) for a flush-mounted box (200) comprising an elongate element (100) provided with an intumescent material (110), the elongate element being adapted to be threaded through an electrical conduit passage opening (240) of the flush-mounted box and comprising retaining means (120) capable of cooperating with an internal part of the flush-mounted box to fix the elongate element to the flush-mounted box in such a way that the elongate element extends mainly outside the latter.