§01 — What the building demands
Conditions inside occupied buildings, tunnels and transport infrastructure
A building’s cable system is divided by function. General power and lighting circuits sit in conduit, trunking or above ceilings; risers carry the building load vertically across fire compartments; and a small group of circuits — fire pumps, smoke extraction, emergency lighting, fire lifts and evacuation systems — has to keep working while the building around them burns. Route conditions vary too: dry partitions, humid plant rooms, and tunnels where vibration, water and smoke behaviour are design issues.
| Application area | Condition in service | What the cable must do |
|---|---|---|
| Final circuits and socket outlets | Conduit or trunking, 450/750 V class | Conductors that pull cleanly and terminate reliably |
| Risers and main distribution | Vertical runs, high load density, compartments | 0.6/1 kV cable with fire-stopped penetrations |
| Occupied public areas | Atria, malls, stations, escape routes | Low smoke and acid gas so escape routes stay usable |
| Life safety circuits | Fire pumps, smoke extraction, emergency lighting | Circuit integrity maintained under flame for the rated period |
| Tunnels and metro | Confined, poorly ventilated, wet, vibrating | Flame-retardant low-smoke build with water tolerance |
Three properties are often confused: flame retardance limits fire spread, low smoke keeps escape routes tenable, circuit integrity keeps a circuit operating during a fire.
§02 — Recommended cable families
Families that match building duties, and why
Building wire for final circuits
Single-core conductors in conduit remain the backbone of lighting and socket circuits, solid for fixed wiring and stranded where accessory boxes are tight: see BV and BVR building wire.
Low-smoke halogen-free cable in occupied spaces
Smoke density is measured by IEC 61034, acid gas by the IEC 60754 series and bunched flame spread by the IEC 60332-3 series — written directly into specifications for malls, stations and tunnels. See LSZH control cable.
Circuit integrity for life safety systems
Fire pumps, smoke extraction, emergency lighting and fire lifts need cable that keeps conducting under flame and, depending on the test, shock and water; IEC 60331 defines the tests. See BTTZ, BTLY and BBTRZ fire-resistant cable.
LV XLPE for risers and distribution
Vertical distribution and plant-room feeders take XLPE cable at 0.6/1 kV under IEC 60502-1, derated for grouping and ambient temperature: see LV XLPE power cable.
Armoured cable for buried and external routes
Car parks, external runs and buried sections between buildings need mechanical protection conduit cannot give, which is what steel-tape armouring is for: see YJV22 armoured power cable.
Optical backbone for building services
Data, security and building management run on fibre, immune to electromagnetic noise in a plant room: see GYTA, GYTS and GYTA53 fibre optic cable.
§03 — Risk table
Where building cable specifications fail in practice
| Risk | Typical cause | How it is avoided |
|---|---|---|
| Life safety circuit fails during a fire | Cable chosen for flame retardance only | Specify the circuit-integrity test and duration from the fire strategy |
| Escape route obscured by smoke | PVC-sheathed cable in a densely occupied volume | Low-smoke construction with smoke and acid-gas tests named |
| Fire spreads through a riser | Penetrations not fire-stopped | Fire-stopped penetrations plus bunched-flame-tested cable |
| Cable falls during a fire | Supports that soften or melt | Fire-rated supports and fixing centres |
| Joints compromise the fire circuit | Fire-resistant cable jointed with standard accessories | Joints specified as part of the rated system |
A fire-rated circuit is a system: cable, supports, fixings, joints and terminations all need the same survival time.
§04 — Questions from consultants and contractors
Frequently asked questions
What is the difference between flame-retardant and fire-resistant cable?
Flame-retardant cable limits the spread of fire along a run and is assessed by tests such as the IEC 60332-3 series on bunched cables. Fire-resistant cable maintains circuit integrity while exposed to fire, assessed by the IEC 60331 series. A fire pump feeder needs the second property; a general power circuit normally needs only the first.
Which circuits should be fire-resistant?
Typically fire pumps and their controls, smoke extraction and pressurisation fans, escape-route and emergency lighting, fire alarms and evacuation systems, and fire lifts. The list comes from the fire engineering.
Is LSZH required in the whole building?
Low-smoke requirements normally apply to occupied and public areas, escape routes, tunnels and transport infrastructure, where smoke and acid gas affect evacuation and equipment. Plant rooms and external sections are often specified differently, area by area.
Why is mineral-insulated cable used for fire pumps?
Mineral insulation is inorganic and does not rely on organic materials to hold the conductor in place under heat, so the cable keeps supplying a motor while exposed to flame. Flexible fire-resistant constructions suit long lengths and tighter bending.
§05 — Next step
From cable schedule to a quotation
A quotation that matches installed cost needs the cable schedule with circuit types, the fire strategy’s integrity and smoke requirements, route lengths, installation methods, and any authority specification governing testing. Our testing and certification page lists the reports per delivery.
Send the schedule and fire strategy extract and we will return a construction proposal with sizes and quantities: Request a quotation →