Cable management: when to use trays, trunking or conduit

The short answer is: metal cable trays are for routes with a high volume of cables (server rooms, industrial plants, commercial buildings); plastic trunking is for surface mounting in offices and residential dwellings; conduit is for protecting individual cables during concealed installation in walls, ceilings, and floors. For underground installation, double-walled HDPE pipe is used, while in timber-framed buildings, steel conduit is used to ensure mechanical protection and circuit integrity.

Selection depends on the number of cables, the environment (dust, moisture, outdoor use, corrosive atmospheres), fire safety requirements, and fill capacity: for conduits, the fill capacity is typically up to 40%; for trunking, it is 35% for solid covers and 40% for covers that can be opened.

Types of Cable Management Systems

Cable management systems provide organised cable routing, protection, and ease of maintenance. The choice of type depends on installation conditions, the quantity of cables, fire safety requirements, and budget.

Metal Cable Trays

Perforated trays are the most common type. Perforations provide ventilation for the cables and allow for easy fastening with cable ties.

• Applications: server rooms, industrial sites, commercial buildings
• Dimensions: side height 50–100 mm, width 50–600 mm
• Features: finishes include pre-galvanised, hot-dip galvanised (HDG), or powder coating
• Installation: mounted on brackets or supports with a span of 1.5–2 m (additional supports are mandatory at bends and joints; exact spacing must be determined by load calculations and manufacturer specifications)

Wire mesh trays are lightweight and economical. They offer excellent ventilation and simple installation.

• Applications: offices, shopping centres, data centres
• Dimensions: standard widths similar to sheet metal trays
• Features: lower weight, rapid cable laying, and lower cost
• Installation: mounted on brackets or supports with a span of 1.5–2 m

Solid (non-perforated) trays provide full protection for cables against mechanical damage.

• Applications: routing along walls or in corrosive environments
• Features: require thermal dissipation calculations if the fill capacity is high
• Installation: similar to perforated trays, with a support span of 1.5–2 m

Earthing of metal cable trays. A metal cable route must form a continuous electrical circuit and be connected to the protective conductor (PE); this is a mandatory requirement for metal cable management systems. Sections must be joined to ensure conductive contact (using bolted connections or earth continuity links/jumpers on coated or powder-coated surfaces), and the entire route must be connected to the earthing terminal.

Plastic Trunking

Used for surface mounting in offices, residential dwellings, and shops. Provides an aesthetic appearance with snap-on covers.

• Application: surface mounting on walls and ceilings in dry rooms
• Sizes: from 12×12 mm to 100×60 mm
• Features: flame-retardant PVC; available in white (standard), wood effect, or grey
• Installation: mini-trunking may be adhered; all other types require mechanical fixings (screws, wall plugs)

Flexible conduit

Protective sheath for single cables during concealed installation in walls, ceilings, and floors.

• PVC conduit (grey) – for indoor use only: flame-retardant, but becomes brittle in freezing temperatures and degrades under UV exposure, making it unsuitable for outdoor use
• PE conduit (black) – for outdoor and underground installation; UV-resistant due to carbon black filler; double-walled versions are used for underground applications. For embedding in concrete, use PVC conduit or rigid PVC pipe
• Steel conduit – for installation above suspended ceilings or within voids of combustible structures: requirements for fire containment or enclosed enclosures must be met. Flexible metal conduit generally does not provide sufficient fire containment

Diameters: 16, 20, 25, 32, 40, 50 mm. Selection is based on the quantity and diameter of the cables: wires and cables must lie freely within the conduit without tension. For buildings with combustible structures, the fill capacity should not exceed 40%. For trunking, the fill capacity is typically limited to 35% for solid-walled trunking and 40% for trunking with removable covers. When mounting conduit on exposed surfaces, use clips or cable ties with holders at intervals of approximately 0.3–0.5 m (more frequently on vertical sections) to prevent sagging over time.

Selection Guide

Conditions	Recommendation
High cable density, server rooms	Wire mesh cable trays
Industrial environments, workshops	Perforated cable trays
Surface mounting in offices	PVC trunking
Concealed in walls (brick, concrete)	PVC conduit
Concealed in timber-framed buildings	Steel conduit with fire containment properties
Underground	Double-walled PE corrugated pipe