Walk any half-finished cable run and you can tell who specified it. The straight lengths are almost always fine. It is at the bends, the tees and the joints that corners get cut, sometimes literally. A buyer once sent us a complaint photo of a tray run rusting in streaks at every coupler while the straight sections still looked new. The trays were hot-dip galvanized. The splice plates someone had bought separately to save a few rupees were painted mild steel. Six months in a humid plant and every joint was weeping rust. The accessories, not the tray, set how long the run lasts.
The fittings that make up a run
A working cable tray system is much more than straight lengths. The accessories are what turn it into a routed system: horizontal bends in inside and outside radius, vertical risers and drops, equal and reducing tees, cross pieces, reducers that step the width down, end plates, dividers that keep power apart from signal, splice or coupler plates that join sections, and the covers that keep dust and falling debris off the cable. Get the bend radius wrong and you crush the cable. Get the coupler wrong and you lose both the strength and the earth path. Neither shows up on the day of handover.
Bend radius is a cable spec, not a tray spec
The most common accessory mistake is a bend that is too tight for the cable. Power and data cables each have a minimum bending radius set by the cable maker, often 8 to 12 times the cable outer diameter for armoured power cable, and the tray fitting has to respect it. A sharp 90 degree bend on a wide tray packed with stiff XLPE cable will deform the conductors, and on fibre it can snap the glass outright. Specify the fitting radius from the largest cable in the run, not from the catalogue default. We make bends to a stated inside radius on request rather than forcing one standard radius onto every job.
The coupler is a structural and an electrical joint
A splice plate quietly does two jobs at once. It carries the bending load across the gap between two tray sections, and it carries earth continuity along the run. A weak or loose coupler sags under cable weight at exactly the spot where there is no support beneath it. A poorly bonded coupler breaks the earth path, so the tray can no longer act as a parallel earth conductor. Both faults stay hidden until something goes wrong downstream. Use the coupler matched to the tray section and gauge, bolt it to the maker's torque, and where the run doubles as an earth path, add a bonding jumper across each joint so continuity does not rest on the bolted contact alone.
Match the finish or the joint rusts first
Back to that streaky-rust photo. The rule is simple and it gets broken constantly: every accessory must carry the same finish and grade as the tray it joins. A galvanized run with painted fittings, or a 316 stainless run with 304 couplers, corrodes first at the joint, and a single oxidised splice plate can fail the whole run's insulation-resistance test in four to six years. When you order, put the finish on the accessories line of the PO in the same words as the tray line. We supply fittings from the same coil and the same galvanizing batch as the trays, so the zinc thickness on the bend matches the zinc thickness on the straight.
The accessories buyers forget to order
- Dividers or barrier strips wherever power and signal share a tray, to hold the separation IEC 60364-5-52 expects.
- Earth bonding jumpers and tray earth lugs where the tray is used as a parallel earth conductor.
- Hold-down clamps and cable cleats at vertical risers, so cable weight does not hang off the bend.
- End caps and edge protection on every cut end, to stop cable chafe and edge rust.
- Covers with fixing clips on outdoor or dusty runs, sized to the tray and in the same finish.
Order the accessories on the same line of thinking as the tray: same grade, same finish, same batch. The cheapest splice plate on the job is usually the one that fails the whole run's earth test.
Specifying a full cable tray system, not just straight lengths? We manufacture bends, tees, reducers, couplers, dividers and covers from the same steel and galvanizing batch as the tray, so finish and earth continuity stay consistent across the run.