How do you calculate cable lay length?

Multiply the complete diameter over the layer by the lay ratio. A 12 mm layer at a lay ratio of 10 has a 120 mm lay length, 4.724 in, or 8.33 turns per metre, the Cable Lay Length calculator's own example.

Lay length divided by the layer diameter. Specifications give it as a range for each layer, because too short a lay wastes material and slows the line, and too long a lay makes the cable less flexible and the layer loose. The workbook flags a ratio outside the minimum and maximum you type.

How do you calculate take-up?

Take-up = sqrt(1 + (pi x pitch diameter / lay length)^2), the length of one element per unit length of cable, with the pitch diameter = layer diameter - element diameter. For the calculator's example with 2 mm wires, pi x 10 / 120 gives a take-up of 1.0337: each wire is 3.37% longer than the cable.

How fast must the cage turn?

Cage speed (rpm) = line speed (m/min) x 1,000 / lay length (mm). A 120 mm lay at 30 m/min needs 250 rpm; halving the lay at the same line speed doubles the cage speed, which is why a shorter lay often means a slower line.

Does the workbook hold the lay ratio limits of a standard?

No. Limits differ by standard, product and customer, so you type the minimum and maximum from your own specification for each layer; the example limits are invented.

Does the workbook use macros?

No. It is a plain .xlsx with ordinary formulas, a table and native charts. The Verify sheet re-checks the formulas against fixed test layers and shows Self-check: PASS.

Production and Throughput

Cable Lay Length Excel Template

Lay length = complete layer diameter × lay ratio. Give every stranding and cabling layer a row and see its lay length in mm and inches, its lay ratio against your specification, and from helix geometry the lay angle, the take-up and the cage speed your line speed needs.

Free, and a plain .xlsx with no macros to enable. A CSV with live formulas and a printed how-to guide come with it.

Overview

This cable lay length template is a working Excel setup sheet for process engineers, setters and quality engineers in wire and cable plants. Each stranding, cabling, armouring or taping layer is one row with its complete diameter, element diameter, lay ratio, the specification's limits and the line speed. It ships with nine layers of four fictional constructions, from a 95 mm² conductor to a 12-core control cable, so every tile and chart is filled in when you open it.

Lay length is the layer diameter times the lay ratio: the 12-wire layer of the conductor, 12.5 mm at a ratio of 13, has a 162.5 mm lay, 6.15 turns per metre. From the helix the workbook adds the lay angle (10.9 degrees), the take-up (each wire is 1.85% longer than the cable) and the cage speed: at 120 m/min the first layer's 105 mm lay needs the cage to turn at 1,142.9 rpm.

In the example the 4-core cabling layer was set to a lay ratio of 37 to run faster, above the specification's maximum of 35, so the Dashboard flags it. The armour has the largest take-up, 5.31% at an 18.3 degree lay angle. The download is a plain .xlsx with no macros. A CSV with live formulas is also included for other tools; the dashboard, charts, dropdowns and self-check are in the .xlsx.

What this template includes

Layers table, one row per stranding or cabling layer: construction, layer, lay direction, complete layer diameter, element diameter, lay ratio, the specification's minimum and maximum, and line speed, with a Check column
Per layer: lay length in mm and inches, revolutions per metre, ratio status in words, pitch diameter, lay angle, take-up, element length per km of cable and cage speed in rpm
Dashboard with four tiles (layers, layers out of limits, largest take-up, highest cage speed), a chart of lay ratio against the specification's limits, a chart of cage speed by layer, and the layer table
Method sheet with every formula and its helix geometry, and a Verify sheet that re-checks the formulas against an independent reference and the Cable Lay Length calculator (Self-check: PASS)
Lay length in inches with the exact 25.4 mm per inch
CSV with live formulas for the Layers table; the dashboard, charts, dropdowns and self-check are in the .xlsx

Suggested use case

Use it to set up stranders, cablers and armouring lines from a product specification, to check a setting sheet before a run, or to see how much extra wire a shorter lay will use.

How to use it

On Setup, type your plant name. Every dimension is in millimetres.
On Layers, give each layer of each construction a row: lay direction, complete layer diameter, element (wire, core or tape) diameter, lay ratio, the specification's limits and the line speed.
Fix anything the Check column names.
Open the Dashboard: layers out of their lay ratio limits, the largest take-up and the cage speed each layer needs.

Frequently Asked Questions

How do you calculate cable lay length?: Multiply the complete diameter over the layer by the lay ratio. A 12 mm layer at a lay ratio of 10 has a 120 mm lay length, 4.724 in, or 8.33 turns per metre, the Cable Lay Length calculator's own example.
What is lay ratio?: Lay length divided by the layer diameter. Specifications give it as a range for each layer, because too short a lay wastes material and slows the line, and too long a lay makes the cable less flexible and the layer loose. The workbook flags a ratio outside the minimum and maximum you type.
How do you calculate take-up?: Take-up = sqrt(1 + (pi x pitch diameter / lay length)^2), the length of one element per unit length of cable, with the pitch diameter = layer diameter - element diameter. For the calculator's example with 2 mm wires, pi x 10 / 120 gives a take-up of 1.0337: each wire is 3.37% longer than the cable.
How fast must the cage turn?: Cage speed (rpm) = line speed (m/min) x 1,000 / lay length (mm). A 120 mm lay at 30 m/min needs 250 rpm; halving the lay at the same line speed doubles the cage speed, which is why a shorter lay often means a slower line.
Does the workbook hold the lay ratio limits of a standard?: No. Limits differ by standard, product and customer, so you type the minimum and maximum from your own specification for each layer; the example limits are invented.
Does the workbook use macros?: No. It is a plain .xlsx with ordinary formulas, a table and native charts. The Verify sheet re-checks the formulas against fixed test layers and shows Self-check: PASS.