How to find the right precast cable trough supplier? The purpose of a cable trough is to protect and route the cable, and to ensure that it remains accessible for future maintenance and is able to be buried or exposed on the surface and held up for years to decades with no cracking, misalignment or water or debris entering. Otherwise, no one is aware of it. The answer is, if it doesn’t, it’s not the idea of the cable trough, it’s the supplier’s idea, that’s the problem. This guide helps you determine if a precast cable trough supplier will deliver a system that will reliably protect your cables throughout the entire length of the run and not cause issues the first time anyone needs to gain access to it.
The Decision to Choose a Supplier Is More Than Just the Size of the Troughs and the Price Per Metre
There is more to choosing a Supplier than just the size of the troughs and the price per metre!
Initial comparisons by most buyers are the internal dimensions, cover loading capacity and price per metre. It’s a good beginning, but it overlooks actually how a cable trough performs: how the supplier reinforces and casts it, so it doesn’t crack when loaded; how it connects between sections; how it protects and enables easy access to the cable during the system’s service life.
Cable troughs are subjected to more stress than they appear to be. They support vehicles or pedestrians from the top, withstand soil pressure when buried, must maintain dimensions for covers to fit tightly and, many years after installation, must not be so tight or large that cables are not easily accessible to adherent technicians. A supplier who considers trough production to be a particular structural product, rather than simply “a long concrete channel with a lid”, plans and reinforces accordingly. If one does not, then the sections will appear consistent on the pallet, and will start cracking under load, misaligning at joints, or cover fit problems will arise in a season or two.
Know Exactly What Type of Cable Trough Your Project Needs
It’s good to have an idea of what type of cable trough you’re looking for before comparing suppliers because not all precast manufacturers produce all types.
Power Distribution Cable Troughs
Power distribution troughs are used for high voltage or medium voltage cables and should be large enough to allow for the cable bending radius and heat dissipation as well as be covered depending on the route that the power distribution runs under (under road, under footpath, or open ground).
Telecommunications and Data Cable Troughs
The lower voltage communication cables in telecom and data troughs tend to be more flexible in duct arrangements and separation, as well as cover load, and are generally more suited to lower structural load requirements than power cable applications.
Trafficable Cable Troughs
Trafficable troughs are specially engineered to be installed beneath vehicle traffic, whether in a roadway, driveway or industrial yard. These require reinforcement and cover systems rated for the actual traffic load the cable trough will be subjected to as undersizing this rating is one of the more serious and costly errors in the selection of a cable trough.
Modular and Sectional Trough Systems
Modular systems consist of standard precast sections that are joined end-to-end to create long runs. The fit of the joint and cover seating detail is critical to their performance because if the fit is not consistent over a long run, it will add up to a misaligned cover or fit issue.
With the right category (or combination of categories) in mind, you can select manufacturers to include in your supplier list that specialize in cable protection systems — not just those that manufacture troughs as a smaller variation on a drainage or utility channel product.
Ask About Reinforcement and Cover Load Design
A cable trough manufacturer that understands manufacturing cable troughs will determine the reinforcement and cover system size according to the actual load class that will be applied to the cable trough in service, whether it be pedestrian load, light traffic or full vehicle traffic. Typically, different reinforcement schedules and cover thicknesses are used for each duty rating.
Ask directly what load class the trough and cover system is rated for as well as what reinforcement schedule is used for that load class and if the cover is load rated to match the load class of the trough body. A supplier that responds with information is talking your language. Anyone who characterizes all his troughs as “heavy duty” without qualifying the type of use, should be asked more questions.
Check Their Dimensional Consistency and Cover Fit
With cable troughs, the dimensional uniformity has direct consequences on the ease of covers seating and on the ease of future access by the service technicians. Inquire about the level of control the supplier has over internal dimensions and the top edge dimensions during casting; and how covers are cast, either by rebate, frame or plain flush fit.
Uneven runs in a trough cause covers to rock in the trough, not to lay flush or to become cumbersome to remove and replace for maintenance, making routine cable access an unnecessary chore. Specifically request the supplier’s tolerance for these dimensions as this is one area in which quality may differ most between manufacturers.
Inspect Their Manufacturing Quality Control
Although two cable troughs may have the same nominal specification, their quality may vary due to the way they have been cast. Inquire about the method of casting, the curing process and tests conducted prior to unit delivery.
Here straightness and uniformity of cross-section are important – the cable troughs are generally laid in long continuous lengths where irregularities between each section will multiply on the way. A dense, well-cured finish also is more likely to be chipped-free around edges and cover seats during handling and installation than a rushed pour. These details are good indicators of the discipline and effectiveness of a supplier’s production line.
Request Layout Drawings That Match Your Cable Route
A good supplier will recognise that you have a specific length of route, bends and access requirements, and will work with those to come up with a solution that is a standard section plus the flexibility you need, rather than forcing you to work a standard section. This should include a layout of standard sections, corner pieces and access chambers that make up your specific route and confirmation of bedding requirements for your ground conditions.
Suppliers who can deliver this kind of coordination are going to detect problems in the site, like awkward bend transitions, too far between access points, different load ratings between bends, etc., before the sections are cast instead of after they are delivered to the job site. When a supplier just provides a standard length, and doesn’t support layout, you might find yourself with gaps, awkward cuts, or poor access points along the way.
Understand the Installation and Bedding Requirements
Depending on the type of the trough and duty, installation requirements differ. In open areas where traffic is not required, lightweight telecom troughs are generally installed on a compacted bed only, whereas trafficable troughs are usually surrounded by proper concrete or bedded to prevent the trough from shifting or cracking with continued use.
Inquire with your supplier about the types of bedding they require, if they include instructions and whether they have ever installed in a similar project or load class. It’s a costly and inconvenient discovery to have on site when realizing the “simple” trough requires a complete concrete surround to accommodate passing vehicles.
Review Their References and Track Record
The reinforcement schedules and cover details will give you a description of what a supplier claims their troughs can do. Installed runs provides the facts about what they have actually provided. Request some examples of cable trough runs provided for other applications and load classes, and the documentation of its performance, such as straight lines, good cover fit, and no cracking over time.
What does make a difference more than a specification sheet is a trough that is still straight, solid and accessible years after installation.
Red Flags to Watch Out For
Some suppliers have loopholes that can be seen in a few warning signs:
- They give fuzzy answers to the question of load rating for trafficable applications.
- They have no clear way of matching sections to your particular cable route.
- They do not fit the cover properly in sample units.
- They charge prices that are significantly lower than other suppliers and cannot give any explanation for the difference.
None of these will exclude a supplier but two or three in combination are a good indication to take a step back and ask more questions before committing to an order.
Final Thoughts Precast Cable Trough Supplier
It’s a matter of understanding the “load” and “access” of your project, and ensuring the supplier designs for these conditions — as well as reinforcing as needed, fitting the covers precisely, and manufacturing the project with care and layout, and not just according to a standard catalogue section. If you do this, your cable trough becomes what it’s designed to be: a reliable protector and routeway for cables, which is never hard to access when problem-solving is required, and never a second thought.