Cable Tray Supports at 1.5 m Centres: Layout and Quantity Calculation

This guide uses 1.5 m between successive supports along a straight cable tray run as its planning basis. It explains preliminary quantities and the information needed for a supply enquiry.

Before installation, check the actual tray and support load data, cable weight, attachment details and approved project requirements. A 1.5 m layout does not establish the capacity of every tray size or thickness; some arrangements require shorter spans or additional supports.

Support span is different from section length

A support assembly transfers tray and cable loads to the supporting structure. It may be a wall bracket, a suspended trapeze or another approved arrangement. The span is the distance between successive supports along the tray.

You can order 3 m straight sections while planning support locations at 1.5 m centres. Section length alone does not determine the permitted support span or the position of a joint. Follow the selected system’s instructions for splice placement and support details.

Estimate support quantities

For a simplified, isolated straight run, assume a support at each end and no end overhang:

Number of spans = run length divided by 1.5 m, rounded up.

Number of supports = number of spans + 1.

• 3 m run: 2 spans and 3 supports.
• 6 m run: 4 spans and 5 supports.
• 12 m run: 8 spans and 9 supports.
• 30 m run: 20 spans and 21 supports.

For a 10 m run, the estimate gives 7 spans and 8 supports. Illustrative positions are 0, 1.5, 3, 4.5, 6, 7.5, 9 and 10 m, leaving a final 1 m span. This explains quantity arithmetic rather than prescribing an installation drawing. Review actual end conditions and joint locations separately.

Count the run, rather than multiplying each section separately

Where an approved continuous layout shares support locations, multiplying every 3 m section by three supports can overcount. In the simplified example, two 3 m sections forming a 6 m run need five support positions, rather than six.

A support count is also different from a threaded-rod count. For example, a trapeze may use a cross-member and two rods, subject to its design. See the fixing accessories guide.

Review fittings and the full support assembly

Bends, tees, crosses, elevation changes, expansion joints and end details may need local supports in addition to the straight-run estimate. Use the selected system’s fitting support details rather than assigning one universal extra-support quantity to every fitting.

Check cable, cover and accessory loads; tray geometry and material; load tables at the proposed span; support members and connections; structural attachments; and required deflection limits. For trapeze supports, the distance between the hanger rods is a different dimension from the spacing between successive trapezes along the route. Read the strut channel selection guide.

Request a complete supply scope

Send route drawings, lengths, levels, tray dimensions and finish, cable weights, the proposed 1.5 m support layout, fitting details and structural attachment information to Rovana Trade. Request separate quantities for straight sections, supports, rods, fixings and accessories.

Technical reference

OBO’s system selection guide explains the relationship between load and support spacing. It recommends not exceeding 1.5 m where possible for its systems, excluding wide-span trays. This is product-specific guidance, rather than certification of a Rovana product or a universal installation rule.