SettingsSettings for this calculationUS
The measured length of straight tray in this run.
Measure the straight tray only. Fittings are counted separately below because each one earns support on its own terms rather than by its length, and a bend that happens to fall between two hangers is exactly the case this calculation exists to catch.
Tools needed: Measuring wheel or laser distance meter, Marked-up containment layout
The largest support interval the delivered tray's load/span class allows.
Read this off the load/span table for the tray you actually received, at the load it will actually carry — not off the drawing. Substituted material is the commonest way a run ends up under-supported: the spacing was drawn for a class the yard did not ship.
How many changes of direction in the horizontal plane this run contains.
Count every elbow that turns the tray left or right, whatever its radius. A bend takes load into the fitting from two directions at once, so hanging it from one side alone lets it rotate about the surviving hanger.
How many inside or outside vertical bends the run turns through.
Count each vertical elbow, whether the tray is climbing or dropping. Vertical runs carry their load along a different axis and need supports rated for that direction; a horizontal hanger turned on its side is not a riser support.
How many three-way branch fittings sit in this run.
A tee is loaded from three directions and is one of the few places where the branch can be the heavier side. Support it near the fitting itself rather than trusting the branch's own first hanger to hold the junction.
How many four-way cross fittings sit in this run.
Crosses are rarer than tees and concentrate more load in one place. Where four tray sections meet, the joint is the least stiff part of the assembly and wants its support close.
How many movement joints are fitted along this run.
An expansion connector needs a support close on each side so the joint can open and close rather than dragging the neighbouring span with it. The gap it is set to comes from the manufacturer's table against the temperature range the run will see — aluminium moves further per degree than steel over the same length.
Whether each bend, tee and cross is hung from one side or from both.
Hanging from both sides is the common practice and the default here, because a fitting supported from one side only can rotate about that single point under the weight of the tray beyond it. Some manufacturers permit a single support within a stated distance of the fitting; if yours does, select one and note the permitted distance on the layout.
Support positions required
27 supports
The straight-run count is exact arithmetic against the span you entered; the fitting allowance is installation practice and should be checked against the tray manufacturer's instructions for the fittings you hold.
- Supports along the straight run
- 11 supports
- Extra supports at bends, tees and crosses
- 14 supports
- Extra supports at expansion connectors
- 2 supports
- Spacing achieved between straight-run supports
- 9.8 ft
- Fittings counted
- 7 fittings
They open the calculator with your figures already in it
Cable Tray Support Position Count Calculator: 27 supports — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- NEMA VE 2, Cable Tray Installation Guidelines — installation practice places supports adjacent to fittings and on both sides of an expansion connector, rather than relying on the straight-run spacing through a change of direction
- Straight-run count = ceil(run length ÷ maximum permitted span) + 1, the standard end-plus-interval count for evenly spaced supports along a line
- RULE OF THUMB, stated as one: the default of two extra supports per fitting is the common practice of hanging a bend, tee or cross from both sides so it cannot twist. It is a practice, not a clause — confirm the number against the tray manufacturer's own installation instructions for the fitting you have.
Inputs used
- Total Straight Run Length
- 98 ft
- Maximum Permitted Span for the Tray Class Delivered
- 10 ft
- Horizontal Bends in the Run
- 4
- Vertical Bends and Risers in the Run
- 2
- Tee Fittings
- 1
- Cross Fittings
- 0
- Expansion Connectors
- 1
- Supports Provided at Each Fitting
- Two — support on both sides of the fitting
Intermediate steps
- Supports along the straight run
- 11 supports
- Extra supports at bends, tees and crosses
- 14 supports
- Extra supports at expansion connectors
- 2 supports
- Spacing achieved between straight-run supports
- 9.8 ft
- Fittings counted
- 7 fittings
Confidence note: The straight-run count is exact arithmetic against the span you entered; the fitting allowance is installation practice and should be checked against the tray manufacturer's instructions for the fittings you hold.
What this calculation does not cover
- Counts positions, not hardware. Trapeze channel, rod, beam clamps and anchors are a separate take-off, and the deck type decides most of it.
- Assumes the entered span is permitted for the tray as delivered and as loaded — a substituted section or a grown cable schedule invalidates it before this count does.
- Says nothing about seismic bracing, which is designed under the loading standard the local building code adopts and is additional to gravity support.
Estimated cost — your price
This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-02 · in the site-wide review of 2026-09-06 · v1.0.1
Regulatory standards & verification citations3
- NEMA VE 2, Cable Tray Installation Guidelines — installation practice places supports adjacent to fittings and on both sides of an expansion connector, rather than relying on the straight-run spacing through a change of direction
- Straight-run count = ceil(run length ÷ maximum permitted span) + 1, the standard end-plus-interval count for evenly spaced supports along a line
- RULE OF THUMB, stated as one: the default of two extra supports per fitting is the common practice of hanging a bend, tee or cross from both sides so it cannot twist. It is a practice, not a clause — confirm the number against the tray manufacturer's own installation instructions for the fitting you have.
Cite this page
Your workspace
Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.
Protection this work requires
- Stop and check first. Textured ceiling coatings, board behind panels, floor tiles and bitumen adhesive in older buildings — built before asbestos was banned or phased out where you are — can contain asbestos, and drilling or sanding them releases fibres. Do not disturb it — have it sampled first. This is not a job for better PPE.
Tools and safety for this job
To first-fix electrical. Generic types, no brands, no prices.
- Assume every cable is live until proved dead at the point you will touch, with a two-pole tester you have just proved on a known source.
First-fix electrical: This site does not publish a tool list for electrical installation work. In every market it serves, fixed wiring is either reserved to a registered electrician or notifiable to a building authority, and the failure mode is a fire or an electrocution months later rather than a visibly bad job on the day. The calculator gives you the quantities to discuss and to buy against. The installation is a job for a qualified electrician, and the certificate they issue is the point of them.