Cable Tray

How to Choose a Cable Tray System for the Cable Route and Load

Cable tray selection starts with the cables the system needs to support and the path those cables must follow. Tray dimensions alone do not determine whether a system is suitable. Cable type, total cable load, support spacing, bends, elevation changes, environmental exposure, and future additions all affect the layout. Plan the route first, then choose the tray construction, support hardware, and transition details that match the complete installation rather than sizing one straight section in isolation.

• Still specifying the conductors and cable assemblies? Start with electrical wire and cable.
• Need structural hardware for wall, ceiling, or framing attachment? Compare straps and supports.
• Transitioning part of the route into conduit? Review conduit fittings and connectors.

Choose the Tray Style Around Cable Support and Ventilation

Common cable tray formats solve different support problems. Ladder-style tray provides open support at intervals, ventilated or trough designs provide more continuous support, wire-mesh or basket systems offer flexible routing for lighter cable groups, and solid-bottom designs provide greater containment while reducing open-air ventilation. The correct format depends on the cables, route, environment, and project requirements.

A 60-ft power-cable route and a 60-ft low-voltage communications run may therefore call for different tray construction even when both follow the same corridor. Decision rule: choose the tray format from the supported cable and installation requirements first, then determine width and depth.

Size the Tray for Cable Fill and Future Capacity

A tray should not be selected only because the existing cable bundle physically fits inside it. The permitted arrangement depends on the cable types, sizes, and applicable installation rules, and projects that are likely to expand also need deliberate spare capacity. Overfilling at the beginning makes later additions harder and can complicate separation, cable access, and maintenance.

Consider a 100-ft route that is expected to pick up several new circuits during the next equipment expansion. Selecting the smallest possible tray can turn that future work into a second support installation. Record the current cable schedule and expected additions before sizing the route rather than estimating capacity from bundle diameter alone.

Calculate the Supported Load Before Setting Support Spacing

The tray, cables, fittings, and any concentrated loads between supports create the installed load that the support system has to carry. Support spacing cannot be copied from another project simply because the tray width looks similar. Tray construction, material, span, cable weight, support arrangement, and manufacturer data all affect the allowable installation.

A tray carrying a light communications bundle over a short span is a different structural condition from a wider tray carrying heavy power cables. Decision rule: establish the cable and tray load first, then use the tray manufacturer’s span and support information to lay out brackets, channel, or other structural supports.

Plan Horizontal Bends, Vertical Changes, and Branches as Part of the Route

Real cable-tray runs rarely stay straight from end to end. Direction changes, elevation changes, tees, branches, and transitions affect both the tray layout and the cable path. Tight or poorly planned changes can make cable installation difficult even when every straight section has enough capacity.

On a route that turns around two building columns and then drops to equipment, mark those changes before calculating straight-section quantities. Where the cable leaves the tray and enters an enclosure, coordinate the termination with appropriate cable glands and cord grips or other fittings identified for the cable and enclosure involved.

Coordinate Cable Tray With Boxes, Conduit, and Equipment Entries

A tray system normally connects to other wiring methods somewhere along the route. Cables may leave the tray for an enclosure, continue through conduit, enter equipment, or reach a splice or transition point. Those interfaces should be designed along with the tray rather than improvised after installation.

If several cables leave a tray at one equipment location, plan enough space for bending, strain relief, and accessible connections. Where splices or taps require an enclosure, use properly sized junction boxes and enclosures. General-purpose transition and mounting parts can also be coordinated through Lumera’s electrical fittings category.

Match Tray Material and Hardware to the Environment

Indoor dry spaces, rooftops, damp areas, corrosive environments, and industrial locations can place very different demands on tray materials and mounting hardware. Material and finish should therefore be selected from the actual exposure rather than appearance alone. Fasteners and supports need the same environmental consideration as the tray itself.

A rooftop run exposed to moisture and weather should not automatically reuse hardware specified for a dry electrical room. Coordinate brackets, anchors, bolts, and other attachments through appropriately selected electrical hardware and fasteners. If boxes are installed along an exposed route, use enclosures identified for those conditions rather than indoor boxes with improvised covers.

Keep Cable Support Separate From Simple Cable Bundling

Cable ties are useful for organization and for applications where the specific product is intended to secure a cable or bundle, but they are not automatically a substitute for the structural support provided by a cable tray system. Tray supports, cable restraints, and bundling products perform different jobs.

For example, grouping six small cables neatly inside a tray does not change the tray’s structural support requirements. Use cable ties and tie wire only where their ratings and installation method suit the application, and keep the tray and support schedule based on the actual cable load.

Consider Grounding and Bonding as Part of the Complete Installation

Metal cable-tray installations can involve grounding and bonding requirements that depend on the tray system, fittings, continuity, cable method, equipment, and applicable electrical rules. Do not assume that mechanical contact between tray sections or nearby metal equipment automatically establishes the required electrical path.

Before installation, review the tray manufacturer’s joining and bonding requirements along with the project electrical design. Lumera’s grounding and bonding hardware covers the separate connector and bonding side of the system. Permanent building-wiring installations should be reviewed and installed by a qualified electrician in accordance with applicable requirements.

Ordering Cable Tray for a Larger Project

For larger cable-management projects, build the material schedule from the route rather than ordering straight tray sections first. Record tray type and size, straight-run length, direction changes, elevation changes, support locations, cable entries, material or finish, and required hardware. This makes it easier to keep tray sections, supports, fittings, and cable-transition components coordinated during purchasing and installation.

Request a Cable Tray Project Quote

For larger quantities or multi-route installations, request a project quote after the cable route and support requirements have been established.

Have these details ready:

• Tray type or required construction
• Tray width, depth, and overall route length
• Cable types and approximate quantities
• Estimated supported cable load
• Horizontal and vertical bends
• Tees, branches, reducers, or other route changes
• Support method and mounting surface
• Indoor, outdoor, damp, or corrosive environment
• Material or finish requirements
• Equipment, box, or conduit transition points

For projects with several cable routes, you can also submit your cable-tray schedule so each run remains tied to the correct dimensions, supports, fittings, and environment.

Cable Tray FAQs

What is the difference between cable tray, wire duct, and conduit?

Cable tray is an open support system for routing supported cable, conduit encloses conductors or cables inside a raceway, and wire duct is commonly used to organize wiring within panels or equipment. They often appear on the same project rather than replacing one another. Lumera’s cable tray vs. wire duct vs. conduit guide compares the three systems in detail.

How do I know what size cable tray I need?

Start with the type, size, and quantity of cables that will occupy the tray, then apply the applicable fill and installation requirements for those cables. Also consider future additions before choosing width and depth. A tray should not be sized from bundle diameter alone because cable arrangement and permitted fill can change by cable type and installation.

How far apart should cable-tray supports be?

Support spacing depends on the tray system, material, span rating, cable load, fitting locations, and manufacturer instructions. There is no single spacing value that applies to every tray. Build the support layout from the exact tray data and installed load, then coordinate brackets and structural hardware with the project’s support requirements.

Does metal cable tray need to be grounded?

Grounding and bonding requirements depend on how the metal tray is used, its listed system components, continuity between sections, and the electrical design. Do not assume mechanical assembly alone satisfies every bonding requirement. Review the tray manufacturer’s instructions and applicable electrical rules, and use properly selected grounding and bonding components where required.

Can cable tray be installed outdoors?

Yes, when the tray system, supports, fasteners, cables, and connection hardware are all suitable for the actual exposure. Moisture, UV exposure, chemicals, and corrosion can affect material selection. Any enclosures added along an exposed route should also suit the location; Lumera’s weatherproof boxes cover that separate enclosure requirement.