Cable Trays

A cable tray is a structural support system that routes and organises power, control, and instrumentation cabling throughout an industrial facility, holding cables in an open, accessible pathway instead of sealing each one inside its own conduit run.

Getting the details right takes coordination across several engineering disciplines, not just one. The tray style, material, fill percentage, separation between cable types, and how the route interacts with structural steel and piping all have to line up. 

What Is a Cable Tray?

In Canada, cable tray design and installation fall under the Canadian Electrical Code (CSA C22.1), with the exact requirements depending on the code edition and jurisdiction in force. In general terms, a cable tray is a structural support system, an assembly of units and associated fittings built to support cables and raceways, and NEC Article 392 in the U.S. describes it in similar terms. The two codes don’t always classify or treat cable tray identically (covered later in this guide), so confirm the specifics against the code edition in force for your project. Canadian requirements take precedence for facilities in Canada.

In practice, a cable tray looks less like a pipe and more like an open shelf, ladder, or wire basket running along walls, ceilings, or structural steel, carrying dozens or hundreds of cables side by side. Process plants, oil and gas sites, and large manufacturing buildings commonly use tray systems, often because it’s easier to add cable later than to pull it through a full conduit.

Cable Tray vs Tray Cable: Two Different Things

The terms cable tray and tray cable are often confused, even in publications aimed at electricians. A cable tray is the structure described above. Tray cable, known in the U.S. as TC cable after its NEC Article 336 rating, is a type of multiconductor cable manufactured with extra jacketing that, when properly listed and rated for the application, can be installed directly in a tray without individual conduit.

A simple way to keep the two straight: the tray is the shelf, and tray cable is one type of product allowed on it. Whether a given cable needs to be tray-rated depends on its classification and the tray’s exposure. That’s a separate question from what the tray itself is.

Why Facilities Use Cable Tray Systems

Cable tray exists as an alternative to routing every cable through individual conduit. Conduit still has its place, particularly where cables need full physical enclosure, but tray systems offer practical advantages that matter over a facility’s life, not just during construction:

• Flexibility for future changes: new cables can usually be laid into an existing tray run instead of being pulled through an already congested pipe.
• Faster installation for high cable counts. One tray run can often carry cables that would otherwise need many separate conduits.
• Easier inspection and maintenance. Cables generally sit in an open or ventilated channel rather than a sealed pipe.
• Better heat dissipation in many cases. Heavily loaded power cables can run cooler in open air than when packed tightly inside conduit.

These advantages are why tray systems are common in industrial buildings, process facilities, and data centres, particularly where cable counts are high, and the facility is expected to change over time.

Cable Tray Types: Ladder, Solid Bottom, and Wire Mesh

Most cable tray falls into one of three general styles, plus a couple of secondary variations worth knowing.

Ladder Cable Tray

Ladder cable tray consists of two parallel side rails connected by individual rungs at regular intervals, like a ladder. The open design suits heavier power cables that need good ventilation and don’t require a solid surface underneath, and it’s widely used on large industrial and process projects.

Solid Bottom (Trough) Cable Tray

Solid bottom cable tray, also called a trough, provides a continuous, enclosed base beneath the cables. It typically offers more physical protection than ladder tray, works well for smaller or more sensitive cables, and tends to trap more heat. Bringing cables in or out along the run often means cutting the tray or using a fitting, depending on the specific product.

Wire Mesh (Basket) Cable Tray

Wire mesh cable tray, sometimes called a cable basket, is formed from welded steel wire in an open grid pattern. It’s often lighter and easier to field-fit than ladder or solid bottom tray, and it’s commonly chosen for lower-voltage data, communication, and instrumentation cabling. However, some wire mesh products are also rated for power applications.

Ventilated, Perforated, and Channel Trays

A few additional styles round out the family. Ventilated or perforated trough tray sits between solid-bottom and open designs, with openings in the base that allow some air circulation and drainage, generally offering more protection than ladder tray. Channel tray has a smaller profile and is typically used for light branch runs and cable drops off a larger backbone tray, rather than as a primary route.

Cable Tray Materials and Environmental Considerations

The tray style determines how cables sit and how much ventilation they get. The material determines how well the tray withstands its surroundings.

Steel (Painted and Galvanised)

Galvanised steel is a common choice for industrial applications, generally offering solid mechanical strength at a moderate cost. It can be pre-galvanised before fabrication or hot-dip galvanised afterwards. Hot-dip galvanising after fabrication can offer better corrosion protection at cut edges and welds, though actual performance depends on coating thickness, fabrication quality, and the specific environment.

Aluminum

An aluminium tray is lighter than an equivalent steel tray, roughly 60% of the weight according to manufacturer data, which can simplify support requirements and installation, particularly in retrofits into existing structural steel. It resists corrosion well in many atmospheric conditions, though performance varies by alloy and environment, and it typically costs more than galvanised steel while suiting fewer aggressive chemical environments.

Stainless Steel and Fibreglass (FRP)

Where environmental conditions are more aggressive, particularly chemical processing areas, wastewater facilities, or coastal and marine sites, stainless steel or fibreglass-reinforced plastic (FRP) trays are often specified despite the added cost. Stainless steel resists a broad range of corrosive exposures, with actual performance depending on the specific grade and the chemicals involved. FRP can resist corrosion even more broadly, depending on the resin and formulation. However, most FRP products are combustible to some degree, so confirm fire performance based on the product’s testing and listing.

How Engineers Select the Right Type, Material, and Size

Choosing a cable tray isn’t a single decision. It’s the product of several factors evaluated together:

• Cable weight and count. Heavier power cables often call for ladder tray, which offers higher loading capacity, while wire mesh can work well for lighter instrumentation or data cabling.
• Environmental exposure. Outdoor, corrosive, or washdown-heavy environments often push the material choice towards stainless steel or FRP, while typical indoor industrial areas can be well served by galvanised steel or aluminium.
• Ventilation needs. Cables that generate a lot of heat can benefit from an open or ventilated design. In contrast, cables that need more physical protection may suit a solid bottom tray better.
• Available space and routing path. Tray width, depth, and the number of bends or elevation changes along the route affect both which style fits and how many fittings the run needs.

None of these factors sits in isolation, and fill capacity is covered in more detail next.

Cable Tray Sizing and Fill Calculations

Cable tray fill capacity, the percentage of a tray’s cross-sectional area that cables can occupy, is set out in the applicable electrical code, CSA C22.1 in Canada, with NEMA VE-1 in the U.S. providing related tray construction, performance, and load classification standards that the electrical code references. Rather than filling a tray to its physical limit, the governing rules set a maximum fill percentage so cables retain room for heat dissipation and future additions.

Fill calculations account for each cable’s diameter, the tray’s usable width and depth, and, for power cables, the derating effects of grouping multiple current-carrying conductors close together. Because the numbers depend on the specific loading class and cable mix for a given project, the electrical discipline finalises them against the manufacturer’s engineering data rather than a single universal formula.

Cable Tray Support Spacing and Structural Considerations

Cable trays need regular structural support along their runs. The required spacing depends on the tray’s construction, loading class, and cable weight, and it’s set using the manufacturer’s load-span tables together with the governing structural calculations, since a higher-rated tray can sometimes span further even when carrying a heavier load. This is one of the clearest places where cable tray design depends directly on structural engineering: supports must tie into structural steel, concrete, or dedicated trapeze hangers sized to carry the tray’s fully loaded weight, plus any seismic bracing the site requires. Support spacing that looks fine on an electrical drawing can still create a structural conflict if it wasn’t checked against the steel it’s meant to hang from.

Cable Separation Requirements

Cable separation requirements exist to help keep different classes of cabling (power, control, instrumentation, and communications) from interfering with or damaging each other. Power cables can induce electrical noise into nearby low-voltage instrumentation or signal wiring, and mixing cable classes without proper separation, whether through physically separate trays or a divider strip within a shared tray, can create both a performance problem and a code compliance issue.

The exact separation requirements depend on several factors, among them voltage levels, cable classification (including Class 1, 2, and 3 circuit distinctions), cable construction and shielding, hazardous area classifications, and the applicable electrical code and authority having jurisdiction. On many process and industrial sites, instrumentation and control cabling is run in its own dedicated tray system, separate from power distribution, which can help protect signal integrity and simplify future tie-ins.

Coordinating Cable Tray Design Across Disciplines

Cable tray design rarely belongs to a single discipline. On a typical project, electrical engineering determines cable counts, tray type, and fill, while Instrumentation & Controls (I&C) adds signal and control cabling with its own separation needs. Structural engineering typically confirms that the tray’s supports, spans, and seismic bracing tie properly into the building or rack steel, and civil and piping disciplines need to confirm the routing doesn’t clash with equipment, walkways, or pipe racks. The exact division of responsibilities varies by project, owner, and contract structure, but these disciplines often work at the same time from different drawings.

When disciplines work from separate, disconnected drawings, tray routing conflicts can become a costly source of field rework: a tray designed before a pipe rack was finalised, a support that was never checked against updated structural steel, or a routing path that turns out to clash with mechanical equipment only after fabrication is already underway.

Designing for Accessibility and Future Additions

A cable tray that’s technically compliant on day one can still cause problems later if it wasn’t designed with maintenance accessibility in mind. Trays routed too close to structural steel, piping, or other equipment can be difficult or unsafe to reach once the facility is operating, slowing inspections and cable replacements alike.

Planning for future additions matters just as much. A tray sized exactly to today’s cable count, with no spare fill capacity and no room in the route to add a parallel run, can force a costly re-route when new equipment arrives, depending on the tray’s load and support capacity, fill limits, access, and the code in force at the time. Leaving reasonable spare capacity, in both fill percentage and physical routing space, is a design decision worth weighing early, since it can help avoid a larger one later.

Cable Tray vs Conduit vs Wireway

Choosing between cable tray, conduit, and wireway comes down to cable count, physical protection needs, and how likely the routing is to change over time. Conduit fully encloses each run and offers strong physical protection, but it installs more slowly for high cable counts and is harder to modify later, since you have to pull new cables through an existing pipe. Cable tray trades some enclosure for openness, which can make it faster to install and easier to add cables to later, a large part of why it’s widely used on large industrial projects with high cable counts. A wireway, or cable trough, sits between the two: a fully enclosed channel that can offer protection similar to conduit while typically being easier to access along its length, often used for shorter runs or where individual cables need to be pulled out at multiple points.

None of the three is a universal answer. Many industrial facilities use all three in different areas: conduit where cables need full protection or run underground, cable tray for the long, high-count backbone runs between areas, and wireway for shorter, more contained sections near panels and equipment.

Cable Tray Code Requirements: Canadian and U.S. Standards

In Canada, cable tray installations fall under the Canadian Electrical Code (CSA C22.1), and Vista Projects designs to this code on facilities across Alberta, Saskatchewan, and other Canadian jurisdictions. Vista’s engineering work is carried out under licensure from APEGA and equivalent provincial engineering regulators, while the authority having jurisdiction in each province administers and enforces the electrical code. For U.S. equivalent reference, cable tray installations there fall under NEC Article 392, with NEMA VE-1 addressing tray construction, performance, and load classification and NEMA VE-2 covering installation guidelines. Code adoption, editions, and amendments vary by jurisdiction, so confirm the version in force where the work is performed. Canadian requirements take precedence for work performed in Canada.

Certifications and licensure requirements vary by jurisdiction. This article reflects Canadian standards and Alberta provincial regulations. For projects in other provinces or jurisdictions, verify requirements with the appropriate provincial authority having jurisdiction.

One nuance worth knowing: NEC and CSA C22.1 don’t necessarily classify cable tray the same way. Some U.S. code discussion debates whether a cable tray counts as a “raceway” under a given NEC section, since the NEC treats cable tray as its own distinct wiring method in some contexts while grouping it with raceways in others. Canadian guidance generally identifies cable tray as a raceway under CSA C22.1, so that the classification can differ by code. On any project where a classification question affects a design decision, for instance, fill calculations or fire-stop requirements, confirm directly against the applicable code edition and the authority having jurisdiction rather than assuming the same answer carries over between codes.

Grounding and Bonding Cable Tray Systems

A metallic cable tray run needs to be electrically continuous and properly grounded along its length. This provides a safe path for fault current and, in some designs, lets the tray serve as an equipment grounding conductor, depending on applicable code requirements and the tray’s specific listing, identification, and marking for that use. In Canada, this work falls under CSA C22.1, alongside CSA Z462 for electrical safety practices and provincial OH&S requirements. Bonding jumpers are commonly used across sections, expansion joints, and fittings where the tray’s natural continuity might otherwise be interrupted. The electrical discipline finalises grounding and bonding details. Still, check them against the tray manufacturer’s specific hardware, since not every splice or connector is rated to maintain electrical continuity on its own.

Common Limitations and Challenges of Cable Tray Systems

Cable tray isn’t the right answer everywhere, and it’s worth being upfront about where it falls short.

Physical protection. Because tray systems expose cables more than conduit does, cables in open trays can be more vulnerable to physical damage than in a fully enclosed conduit. However, an open, ventilated design can also reduce moisture and debris buildup compared with a sealed system in some environments. That’s part of why a solid bottom or covered tray gets specified in more exposed or higher-risk areas.

Aesthetics. An open tray is visible in a way conduit isn’t, which can matter in finished or public-facing spaces, though it’s typically less of a concern on industrial or process sites.

Fire safety. Combustible cable jacketing can allow a fire to spread along a cable tray run inside a structure, which is why fire-retardant cable jacketing and fireproofing coatings are often specified on trays that pass through fire-rated barriers. However, actual protection depends on the product’s testing and listing, not the coating alone. Research on fireproofing coatings has found that they can delay heat transfer and ignition under tested conditions rather than prevent it outright. Heavier coatings can also reduce a cable’s ability to dissipate heat, which may require its current rating to be adjusted, a detail that’s easy to miss if fire protection and electrical sizing aren’t coordinated. Most FRP and other plastic tray materials are combustible to some degree, which factors into material selection anywhere fire propagation is a serious concern. However, fire performance varies by specific formulation and should be confirmed against product testing. Where a cable tray passes through a fire-rated wall or floor, the penetration needs a fire-stop system tested and listed for that specific penetration and rated assembly, not just a generically rated product. This requirement is often missed when tray routing is finalised without input from the owner of the facility’s fire protection design.

Installing and Modifying Cable Tray

Cutting, bending, and connecting cable tray sections in the field is a detailed topic in its own right, with techniques varying by tray style and material. That’s a subject for a dedicated installation guide, not this one.

Frequently Asked Questions

What are the three main types of cable tray?

The three main types are ladder, solid bottom, and wire mesh cable tray. Ladder tray uses spaced rungs and suits heavier power cables that need ventilation. Solid bottom tray provides an enclosed base for better physical protection. Wire mesh tray offers a lightweight, flexible option used for data, communication, and instrumentation cabling.

What’s the difference between cable tray and tray cable?

Cable tray is the physical support structure. Tray cable is a type of cable rated for installation in a tray without individual conduit. The two terms are easy to confuse because they use the same words in a different order, but they refer to different things. One is the shelf; the other is a product placed on it.

When should you use cable tray instead of conduit?

Cable tray makes the most sense when cable counts are high and future additions are likely, since you can lay new cables in rather than pull them through an enclosed pipe. Conduit remains the better choice where cables need full physical protection, for example underground runs or areas with heavy mechanical exposure.

What are the disadvantages of cable trays?

Main disadvantages include less physical protection than conduit and greater exposure to dust and moisture in some environments. Routing is also visible in a way that isn’t always desirable in finished spaces, and fire safety considerations require fire-retardant cabling or coatings in some applications.

Is a cable tray considered a raceway?

It depends on the code and edition. Under the NEC, cable tray is sometimes treated as its own distinct wiring method and sometimes grouped with raceways, which comes up in U.S. code discussions. Canadian guidance generally identifies cable tray as a raceway under CSA C22.1, so that the classification can differ by code. Confirm against the applicable code edition and your authority having jurisdiction whenever this distinction matters for a specific design decision.

How much do cable trays cost?

Costs vary widely based on tray style, material, width, length, coatings, and regional pricing, so there’s no single reliable figure. As a general pattern, wire mesh trays tend to be the lower-cost option, galvanised steel ladder trays often sit in the middle, and stainless steel or FRP trays tend to cost more, largely reflecting their corrosion resistance. Getting an accurate number for a specific project means pricing the tray type, material, and length required for your region, along with the engineering that determines those specifications.

Conclusion

A cable tray looks like a simple piece of hardware, but the decisions behind it (style, material, fill, separation, support spacing, and routing) touch nearly every engineering discipline on an industrial project. Getting those decisions right the first time, and keeping them coordinated as a project evolves, often matters more than any single choice made in isolation.

That coordination is where a firm like Vista Projects spends much of its time: keeping electrical, structural, instrumentation, civil, and piping design working from the same current information, so decisions like cable tray routing hold up from early design through construction and into the facility’s operating life. 

Talk to Vista’s engineering team about your next project.