Electrical & Communications Risers

Risers are the vertical shafts and cupboards that carry services between floors: electrical risers with sub-mains, busducts and distribution boards; communications risers with backbone cabling, fibre and carrier equipment; and hydraulic and mechanical shafts with pipes and ducts. Functionally a riser must give services a protected route, give maintenance staff safe access, keep fire and smoke from spreading between floors, stay cool and dry, and have room for future services. Risers are where capacity for new tenants, electrification and EV charging is decided, and where fire separation between floors most often breaks down.

Because risers are behind locked doors, their condition is often unknown to owners and only discovered when a fire engineer or new tenant opens them.

What shortens fitness for purpose:

• Abandoned cables left in place when tenants and carriers change.
• New services squeezed in without fire stopping or support.
• Storage in riser cupboards.
• Demand growth from electrification, data and EV charging.

Risers are long-lived structurally; their usefulness is consumed by each tenancy, carrier and upgrade that adds services without removing old ones.

Broken fire stopping

Every cable or pipe added through a riser floor breaks the fire stopping unless it is reinstated with a tested system. Over years, riser floors become a series of holes packed with foam, mineral wool or nothing, letting fire and smoke travel between all floors. This is one of the most common serious fire defects in existing buildings.

Congestion and abandoned cabling

Cable trays fill with abandoned cables that nobody dares remove, leaving no space for new services, overloading supports, adding fire load and smoke from burning insulation, and making tracing faults slow.

Heat

Distribution boards, busducts and comms equipment in enclosed risers generate heat; without ventilation, temperatures rise, shortening equipment life and causing faults.

Water ingress

Risers next to plumbing shafts and wet areas, or below roof penetrations, get water on electrical and communications equipment.

Access, security and labelling

Riser doors left unlocked, used as cleaners' cupboards or storage, or locked with keys no one can find; equipment unlabelled so isolations are unsafe.

Capacity exhaustion

Risers without spare space or electrical capacity limit what tenants and new uses can do; adding a new riser later is expensive.

Unknown circuits and unsafe isolation

When boards and cables in risers are unlabelled or labels are out of date after fit-outs, electricians cannot be sure what they are isolating. Work on live circuits and accidental outages to other tenants follow.

On a riser walk, every floor

• Open or poorly sealed slab penetrations; foam around cables.
• Overfull trays; cables hanging free; abandoned cables.
• Storage and rubbish in riser cupboards.
• Warm air on opening the door; equipment fans running hard.
• Water staining, drips or corrosion.
• Unlabelled boards and cables; doors unlocked or without fire rating labels.

In the records

• Riser drawings and capacity schedules.
• Fire stopping records with photographs.
• Cabling records and carrier agreements.
• Maximum demand data per riser.

• Riser doors without fire rating labels or closers.

• Carrier equipment installed without approval or records.

Fire stopping failures are almost always cumulative: each contractor breaks a little and nobody reinstates it.

Distinguish missing capacity (no space or electrical headroom) from wasted capacity (abandoned cables, poorly organised trays); the second is far cheaper to fix.

Findings are graded by what they demand: safety (can hurt someone now), failure (failed and damaging the building), condition (distress present and progressing), lifecycle (renewal due on age and exposure), deadline (a regulator or ordinance sets the date), check (investigate before sizing works) and nil (cosmetic or stable).

A single riser floor without fire stopping can compromise compartmentation for the whole building, so riser findings should be graded on what they connect, not how small the gap looks.

An electrical and communications engineer leads, with a passive fire specialist for penetrations and the carriers for their equipment.

• Riser walk on every floor: penetrations through slabs and walls, fire stopping type and condition, doors and their ratings and locks, trays and supports, distribution equipment, labelling, housekeeping, water and temperature, with photographs.
• Capacity survey: free space on trays and in the shaft, electrical capacity of submains and busducts against maximum demand, and fibre and copper backbone capacity.
• Abandoned cable identification by tracing and carrier records, to free space and reduce fire load.
• Temperature logging in risers holding active equipment through a hot period.
• Records review: riser drawings, fire stopping records and carrier agreements.

The report should list fire stopping defects floor by floor, capacity remaining for planned uses, and works needed.

• Fire stopping with tested systems at every floor and wall penetration, recorded with photographs and product details so the next contractor can see what was done.
• Abandoned cable removal, which frees space, reduces fire load and makes faults easier to trace.
• Cable management: new or additional trays and supports, segregation of power and data, and labelling of every cable and board.
• Ventilation or cooling where equipment heat builds up.
• Water protection: drip trays, upstands and relocation of pipes away from electrical equipment.
• Access control and housekeeping: locked doors with managed keys and no storage.
• Penetration permits so every new service is fire stopped and recorded.
• New capacity: additional risers, busducts or backbone where demand will exceed what exists.

• Riser register: a floor-by-floor record of services, capacity and fire stopping, updated after every job.

Fire stopping is priced per penetration or per riser floor, and a whole-building remediation can be substantial in older buildings. Cable removal is priced per riser. Trays by length. Cooling per riser. New risers are major projects involving slab penetrations on every floor, so preserving and recovering capacity in existing risers is usually far cheaper. Fire stopping is code compliance; capacity is lifecycle or tied to the project needing it.

• Australia. The National Construction Code requires service penetrations through fire-rated floors and walls to be protected, with AS 4072.1 setting penetration systems and AS 1530.4 testing; fire stopping is an essential safety measure in annual certification; communications cabling must be done by registered cablers; AS/NZS 3000 governs electrical installations in risers.
• United Kingdom. Approved Document B requires fire stopping of penetrations through compartment floors and walls; BS 7671 governs electrical installations; the Building Safety Act 2022 adds golden thread information duties for higher-risk buildings, including records of fire stopping.
• United States. The International Building Code and NFPA 101 require fire-rated shafts and tested firestop systems; NFPA 70 governs electrical installations and requires removal of accessible abandoned communications cables in many cases; local fire marshals inspect firestopping.

• Riser drawings and capacity schedules.
• Fire stopping records with photographs and products.
• Cabling records and carrier agreements.
• Maximum demand data by riser.
• Riser temperature records.
• Penetration permit records.

• Fire safety certification noting riser fire stopping.
• Records of electrical and communications works by tenants and carriers, with approvals.
• Planned loads such as EV charging and electrification that will use riser capacity.