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Every cable in this segment, summed from the schedule.
Take each cable's published weight per unit length and add them. It is worth doing per SEGMENT rather than for the whole route: a riser carrying eight feeders at the bottom and two at the top is two different loading cases, and sizing the whole run on the heaviest is expensive.
The empty weight of the tray section itself, from the manufacturer's catalogue.
Varies enormously with material and depth: aluminium ladder is light, hot-dip galvanised steel solid-bottom several times heavier, and a fibreglass tray heavier still than its stiffness suggests. Covers, where fitted, are additional and are often forgotten.
Anything strapped to or hung off the tray that is not a cable in it.
Small conduits clipped to the side rail, single-core cleats, a pneumatic line running with the electrical, an earth tape. Individually trivial and collectively not, and the tray is carrying all of it whether the schedule mentions it or not.
Radial ice or lying snow on an outdoor tray, per unit of run. Zero indoors.
Outdoor tray in a freezing climate accretes ice on the tray and on every cable in it, and the accreted mass is a function of the total exposed surface rather than of the cable weight. Take the radial ice thickness from the site's own climate data and work the volume out from the exposed profile.
The point load of a person working in the tray during a pull, applied at mid-span.
The value NEMA VE 1 uses for its rating test is 200 lb (90.7 kg, 890 N), and that is the default here. Raise it where the crew is heavier, where two people will be in the tray at once, or where a cable drum jack or a pulling sheave will be mounted on it.
Centre-to-centre distance between the two supports either side of this segment.
Needed because a point load and a distributed load are only equivalent for a given span — the same person weighs the same on a 1.5 m span and a 6 m one, but the distributed load they represent is four times smaller on the longer span. Use the largest span in the segment.
Total load per unit length
53.78 lb/ft
The headline uses the moment-equivalent restatement of the worker allowance, which is the conservative one. For a deflection check, swap in the smaller figure from the breakdown — using the moment equivalent there overstates the sag by a quarter.
- Uniformly distributed load from the schedule
- 13.78 lb/ft
- Cables in the segment
- 9.41 lb/ft
- Tray self-weight
- 3.02 lb/ft
- Attached conduits and cleats
- 1.34 lb/ft
- Ice or snow allowance
- 0 lb/ft
- Concentrated allowance restated for a moment check
- 40 lb/ft
- Concentrated allowance restated for a deflection check
- 32 lb/ft
- Total load for a moment check, in N/m for the deflection page
- 784.79 N/m
- Total load for a deflection check, in N/m for the deflection page
- 668.04 N/m
- Mid-span bending moment from the total
- 672.19 lbf·ft
They open the calculator with your figures already in it
Cable Tray Loaded Weight Per Unit Length Calculator: 53.78 lb/ft — 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 1, Metal Cable Tray Systems — tray is rated for a uniformly distributed working load applied together with a concentrated load at mid-span, which is why a worker allowance has to be carried alongside the distributed cable weight rather than folded into it
- NEMA VE 2, Cable Tray Installation Guidelines — the concentrated allowance represents an installer standing or kneeling in the tray during a pull, and it is applied where it does most harm, at mid-span
- Restating a mid-span point load as an equivalent uniform load is exact beam statics, and the factor depends on what is being checked: 2P/L matches the bending moment (PL/4 = wL²/8) and 1.6P/L matches the deflection (PL³/48EI = 5wL⁴/384EI). Both are reported because using one where the other belongs overstates or understates by 25%
- Distinct from this site's Cable Tray Center-Span Deflection Calculator, which takes a load per unit length as an input. This one builds that number from the segment's own schedule and hands it over — but hand over one of the two N/m rows in the breakdown, NOT the kg/m headline: that field is a force per unit length and the headline is a mass per unit length, a factor of 9.81 apart
Inputs used
- Cable Schedule Weight per Unit Length
- 9.41 lb/ft
- Tray Self-Weight per Unit Length
- 3.02 lb/ft
- Attached Conduits, Cleats and Accessories
- 1.34 lb/ft
- Ice or Snow Allowance per Unit Length
- 0 lb/ft
- Concentrated Worker Allowance
- 200 lb
- Support Span
- 10 ft
Intermediate steps
- Uniformly distributed load from the schedule
- 13.78 lb/ft
- Cables in the segment
- 9.41 lb/ft
- Tray self-weight
- 3.02 lb/ft
- Attached conduits and cleats
- 1.34 lb/ft
- Ice or snow allowance
- 0 lb/ft
- Concentrated allowance restated for a moment check
- 40 lb/ft
- Concentrated allowance restated for a deflection check
- 32 lb/ft
- Total load for a moment check, in N/m for the deflection page
- 784.79 N/m
- Total load for a deflection check, in N/m for the deflection page
- 668.04 N/m
- Mid-span bending moment from the total
- 672.19 lbf·ft
Confidence note: The headline uses the moment-equivalent restatement of the worker allowance, which is the conservative one. For a deflection check, swap in the smaller figure from the breakdown — using the moment equivalent there overstates the sag by a quarter.
What this calculation does not cover
- The equivalence between a point load and a uniform load holds for a simply supported single span. Continuous tray over several supports redistributes both, generally in the tray's favour.
- No allowance for wind on an outdoor run, nor for the sideways load a cable pull puts on a bend. Both are real and neither is a weight per unit length.
- Cable weight per unit length rises as a tray fills, and the fill limit is a separate check on cross-sectional area rather than on weight.
Add the equipment this sizes
This result is a specification — 53.78 lb/ft — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
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 2026-09-06 · in the site-wide review of 2026-09-06 · v1.0.1
Regulatory standards & verification citations4
- NEMA VE 1, Metal Cable Tray Systems — tray is rated for a uniformly distributed working load applied together with a concentrated load at mid-span, which is why a worker allowance has to be carried alongside the distributed cable weight rather than folded into it
- NEMA VE 2, Cable Tray Installation Guidelines — the concentrated allowance represents an installer standing or kneeling in the tray during a pull, and it is applied where it does most harm, at mid-span
- Restating a mid-span point load as an equivalent uniform load is exact beam statics, and the factor depends on what is being checked: 2P/L matches the bending moment (PL/4 = wL²/8) and 1.6P/L matches the deflection (PL³/48EI = 5wL⁴/384EI). Both are reported because using one where the other belongs overstates or understates by 25%
- Distinct from this site's Cable Tray Center-Span Deflection Calculator, which takes a load per unit length as an input. This one builds that number from the segment's own schedule and hands it over — but hand over one of the two N/m rows in the breakdown, NOT the kg/m headline: that field is a force per unit length and the headline is a mass per unit length, a factor of 9.81 apart
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