Fire Stopping for Cable and Data Upgrades in Commercial Buildings

Cable and data upgrades can compromise fire compartmentation whenever new routes pass through fire-resisting walls or floors. The safest approach is to identify compartment lines before work starts, approve each penetration, use a tested fire-stopping system suited to the complete service configuration, and record the installation before it is concealed.

This gives facilities teams a usable audit trail, helps maintain the building’s passive fire protection strategy and reduces the risk of disruptive remedial work later.

Commercial buildings rarely stand still. Fibre roll-outs, Wi-Fi upgrades, access-control systems, CCTV, tenant alterations and additional power supplies all create pressure for new cable routes. A small opening made above a suspended ceiling may appear to be a minor enabling task, but if it crosses a compartment wall, it becomes part of the building’s fire-safety arrangements.

This guide explains what clients, facilities managers, principal contractors, M&E teams and cabling contractors should coordinate before, during and after cable works in occupied UK commercial property. It provides practical project guidance and is not a substitute for the project fire strategy, product field of application, competent design advice or building control requirements.

Fire-stopping controls at each stage of a cable upgrade

Why do cable upgrades affect fire compartmentation?

Compartment walls and floors are intended to resist the passage of fire and smoke for a defined period. When a cable tray, conduit, trunking or cable bundle passes through that construction, the opening must be treated as a complete penetration-sealing detail. It should not simply be filled with whatever material is available on site.

The challenge is rarely one large, obvious opening. Risk often accumulates through repeated small changes:

• An installer routes a new cable beside an existing fire seal.
• A redundant cable is removed and leaves an unsealed gap.
• A growing cable bundle exceeds the service loading supported by the tested system.
• A cable tray is moved without reassessing the penetration detail.
• A ceiling or riser panel is closed before the completed seal has been inspected.
• Responsibility for reinstatement becomes unclear between the cabling contractor, builder and passive fire contractor.

In an occupied building or busy fit-out, these changes can be difficult to identify once the work is concealed.

Why must cable fire stopping be treated as a complete system?

A compliant fire-stopping detail is a complete system, not simply a tube of sealant or a particular coloured product.

The appropriate detail depends on factors including:

• The wall or floor construction.
• The size and shape of the opening.
• The cable types, quantities and bundle dimensions.
• Whether the services pass through individually, in trunking or on a tray or basket.
• The required fire-resistance performance.
• The supporting construction and position of service supports.
• Movement, maintenance and future-access requirements.

The tested arrangement may also require specific backing materials, minimum annular gaps, seal depths, edge distances and service-support arrangements. Substituting components or altering the geometry can move the installation outside the evidence supporting the system.

A product should therefore be selected against the complete site condition, rather than chosen solely because it is described as fire resistant.

Plan the cable route before anyone drills

Fire-stopping coordination should begin before the cable route is fixed. Start with the current drawings, the project fire strategy and a site walkover.

Drawings are valuable, but occupied buildings often contain undocumented alterations. A targeted fire-stopping site survey can help identify likely compartment lines, existing defects, congested openings and access constraints before the programme is locked.

Route design should minimise both the number and size of penetrations. Where cables must cross a fire-resisting wall or floor, sufficient space should be allocated for a supported fire-stopping detail. New cables should not simply be forced through an existing opening because it appears to have spare space.

The route review should also consider:

• Working height and safe access.
• Asbestos information and intrusive-survey requirements.
• Suspended ceilings and builder’s-work interfaces.
• Occupancy and business-continuity requirements.
• Dust, noise and isolation controls.
• The position of cable supports near the penetration.
• Inspection access before close-up.
• Who will update drawings and asset records.

A five-stage penetration-control process

1. Confirm the compartment line. Identify the relevant wall or floor and its required performance using controlled project information.
2. Survey the proposed route. Record the construction, existing services, openings, seals and access conditions.
3. Select a supported detail. Match the tested or assessed system to the actual substrate, opening and complete cable configuration.
4. Define responsibility. State who approves the opening, installs the fire stopping, inspects the work and accepts the evidence.
5. Hold the close-up point. Do not conceal the penetration until the agreed inspection and photographic records are complete.

For multi-trade projects, a controlled permit-to-penetrate process can provide a clear handover between the contractor creating the opening and the competent installer responsible for reinstatement.

Control cable additions in occupied buildings

Live offices, retail premises, hospitals, schools and managed estates present different challenges from new-build projects. Fire compartmentation must remain controlled while the building continues to operate.

The responsible person’s fire-safety arrangements remain relevant during the works. GOV.UK provides guidance on workplace fire-safety responsibilities, including maintaining appropriate precautions and reviewing the fire risk assessment where relevant.

Project teams should plan how openings will be created, protected, inspected and permanently sealed without leaving uncontrolled gaps between working shifts.

What should happen if a penetration cannot be sealed immediately?

If an opening cannot be permanently sealed as part of the same operation, the temporary condition should be assessed and recorded rather than left as an unplanned hole overnight.

Depending on the building, fire strategy and risk assessment, temporary controls may include:

• Limiting how long the opening remains unsealed.
• Using a temporary fire-stopping arrangement supported for that purpose.
• Changing the work sequence so that sealing can follow immediately.
• Providing additional supervision or fire-watch arrangements where justified.
• Restricting access to affected areas.
• Keeping affected rooms or zones unoccupied.
• Recording and communicating the temporary condition to the relevant building team.

The appropriate control should be determined by competent persons with reference to the building’s fire strategy and current risk assessment.

Can new cables be added to an existing fire seal?

Cables should only be added to an existing fire seal where the system can be identified, remains in suitable condition and permits the proposed cable type, quantity and configuration.

Some modular or flexible cable-sealing systems are designed to accommodate future changes, but only within their documented capacity and installation rules.

Before adding cables, check:

• The system manufacturer and product identification.
• The tested or assessed service range.
• The permitted cable types and dimensions.
• The maximum supported fill or cable loading.
• The remaining capacity within the opening.
• The condition of the existing components.
• The position and adequacy of service supports.
• Whether the proposed change requires components to be replaced or reinstalled.

If the original seal cannot be identified or verified, adding another cable is not routine maintenance. The opening should be reviewed by a competent person before it is altered.

What should you do when an existing cable seal is found?

• Identified and within capacity: Follow the manufacturer’s documented change procedure and update the penetration record.
• Identified but outside its supported capacity: Obtain a revised fire-stopping detail before proceeding.
• Damaged, incomplete or unidentified: Do not add further cables until the condition has been competently assessed.

What should happen when cables are removed?

Removing redundant data, power or communication cables can also affect the performance of an existing seal.

A cable may have formed part of the installed service configuration, and its removal can leave a gap through the fire-stopping material. Pulling cables through the seal may also damage components that remain in place.

Redundant cable removal should therefore include:

• Checking the existing system before work begins.
• Removing the cable without damaging adjacent components.
• Reinstating any resulting gaps using a supported detail.
• Inspecting the completed repair.
• Updating photographs, drawings and the penetration register.

What records should be kept for cable penetration fire stopping?

Good records allow another competent person to understand what was installed, where it is located and what supports its claimed performance.

This information is useful in every managed commercial building and is particularly important where statutory golden-thread duties apply. Official guidance explains the information that must be kept for higher-risk buildings. Project teams should confirm which duties apply to their building and scope of work.

A suitable penetration record should normally include:

• A unique penetration or asset reference.
• The floor, room, riser or zone.
• A marked-up drawing location.
• Before, during and completed photographs.
• Useful scale and wider location context within the photographs.
• The wall or floor construction.
• The opening dimensions.
• The service type and complete cable configuration.
• The cable tray, basket, conduit or trunking arrangement.
• The supporting construction and service supports.
• The manufacturer and product references.
• The tested-system or assessment reference.
• The required fire-resistance performance.
• The installer and installation date.
• The inspection status and inspector details.
• Any approved variations or corrective actions.

Photographs alone are not sufficient if they cannot be connected to a location, penetration reference or supported detail. Equally, retaining a product datasheet does not prove that the installed geometry matches the evidence supporting the system.

Midsummer’s guide to passive fire protection handover packs explains how installation records can be assembled into information the building team can use and maintain.

Which UK requirements may apply?

The requirements applying to cable penetration fire stopping will depend on the building, the work being undertaken and the regulatory framework in force for the project.

Relevant information may include:

• The building’s fire strategy.
• The fire risk assessment and temporary fire-safety arrangements.
• The project specification and design information.
• Manufacturer test evidence and field-of-application documents.
• Building Regulations requirements where the work constitutes building work.
• Handover information requirements.
• Golden-thread duties for relevant higher-risk buildings.
• Client, landlord or estate-management change-control procedures.

For building work in England, fire-safety information may need to be provided at handover under Regulation 38. The government’s Approved Document B collection provides statutory guidance. The correct volume, edition and amendments should always be checked for the specific project.

Project teams should obtain competent technical and fire-safety advice where the applicable requirements or suitability of a proposed detail are unclear.

A practical cable-penetration close-up checklist

Before a ceiling, riser panel or builder’s-work enclosure is closed, the project team should be able to answer “yes” to the following questions:

• Is the penetration in the approved position?
• Has it been assigned the correct asset or penetration reference?
• Does the wall or floor construction match the selected system?
• Are the opening dimensions within the supporting evidence?
• Do the cable types, quantities and bundle sizes match the approved detail?
• Are the cable tray, basket, trunking or conduit arrangements supported?
• Are service supports correctly positioned?
• Are the required gaps, seal depths and edge distances achieved?
• Have debris, temporary packing and redundant combustible materials been removed?
• Are all required system components present and visibly complete?
• Has the installation been labelled where required by the specification?
• Are the photographs legible and connected to the correct location?
• Have before, during and completed photographs been retained?
• Have identified defects been closed out?
• Has the asset register or marked-up drawing been updated?

Close-up should follow inspection and acceptance. It should not be driven solely by the ceiling or fit-out programme.

Common cable fire-stopping mistakes to avoid

Drilling first and designing later

The selected location may not provide enough space for a supported seal, suitable edge distances or the required service supports.

Treating fire-stopping products as interchangeable

Colour does not demonstrate compatibility, suitability or fire performance. Components should not be substituted without appropriate supporting evidence.

Adding cables to an unidentified seal

This may exceed the system’s supported capacity, invalidate the original arrangement or conceal existing defects.

Overfilling a cable opening

A seal that was suitable for the original installation may no longer be supported once additional cable bundles are introduced.

Recording only the finished face

Backing materials, installed depth and concealed components may no longer be visible after the installation is complete.

Allowing the ceiling programme to dictate acceptance

Closing the area before inspection can make defects difficult and expensive to correct.

Failing to record later cable changes

An evidence pack is only useful where change control keeps the information accurate and current.

Removing cables without reinstating the seal

Redundant cable removal can leave gaps or damage the existing system if the penetration is not reassessed.

Frequently asked questions

Does every cable penetration need fire stopping?

Every opening through a fire-resisting wall or floor requires an appropriate treatment that maintains the required performance. The correct solution depends on the construction, opening, services and project requirements.

Can cables be added to an existing fire seal?

Cables should only be added where the existing system can be identified, remains in suitable condition and permits the proposed cable type, quantity and configuration. Otherwise, the opening should receive competent technical review.

Can a cable be pushed through fire-stopping sealant?

A cable should not be pushed through an existing seal unless the system is specifically designed and documented to permit that type of change. Doing so may damage the seal or move the installation outside its supported configuration.

Who is responsible for sealing the opening?

The contract and project controls should state this explicitly. Responsibility should not be allowed to fall between the cabling contractor, builder, M&E contractor and passive fire contractor.

What photographs should be retained?

Records should include wider location context and clear before, during and completed views. The images should connect the penetration reference to the substrate, services, system components and final condition.

Should the fire risk assessment be reviewed after cable works?

The responsible person should consider whether the work or resulting conditions affect the existing assessment and fire precautions. Competent fire-safety advice should be obtained for significant or complex changes.

Can an opening be left unsealed overnight?

An opening should not be left as an uncontrolled condition. Where permanent sealing cannot be completed immediately, suitable temporary controls should be assessed, documented and implemented in accordance with the building’s fire strategy and risk arrangements.

Plan the penetration, not just the cable route

Cable and data upgrades are routine, but uncontrolled openings through compartment walls and floors should not be.

Early surveys, coordinated route design, supported fire-stopping details, competent installation and usable records help protect both the building and the programme. They also make later technology upgrades easier to control because facilities teams can identify what has been installed and whether further changes are permitted.

Engaging an experienced fire-stopping contractor before cable routes are finalised gives the project team time to resolve unsuitable openings, unidentified seals and congested routes before they become expensive programme problems.

Midsummer Fire Protection supports commercial property teams, facilities managers and contractors with surveys, specification-led fire-stopping installation and project evidence.

Planning cable, fibre, CCTV, access-control or data works through compartment walls or floors? Contact Midsummer Fire Protection to discuss route surveys, penetration controls, installation and handover records for your project.