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Guy Wire Installation Guide
Field installation guide for the guy wires of the MMT10 and MMT20 tripod-mast systems: level and stake layout, stake pull-out capacity by soil class, rope and pre-tension, the eleven-step sequence, the acceptance checklist and a blank installation record. Six pages.
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Guy Wire Installation
This guide describes how the guy wires of the mast systems are installed in the field. Whatever the mast height and the number of guy levels, the three rules below do not change.
Every guy level uses the same azimuth lines. Levels are never rotated relative to one another.
The stake radius equals the height of that level's guy collar, so every rope runs at 45°. Permitted deviation on a constrained site: p. 02.
Each level ties to its own stake. Three levels on one line means three stakes.
Power lines. The site must be no closer to an overhead power line than the full height of the mast.
Wind. Do not raise the mast in wind that makes the ropes hard to control by hand; raise it in calm air.
Exclusion zone. While the mast is being raised, nobody stands under it or in its fall direction.
Level and Stake Layout
If the prevailing wind direction is known, set the first line into it.
Extend the opposite line along the same straight line; the mast centre stays exactly midway.
Set the two perpendicular lines with a 3-4-5 triangle: the span between the 3 m and 4 m marks must be exactly 5 m.
Finding the Level Heights
Divide the mast height by the number of levels. Level 1 is at the top; the rest step down at equal intervals, measured from the ground: three levels on a 12 m mast → 12 · 8 · 4 m.
Radius = height. Start the tape at the mast axis and walk out along the line to the same figure.
Rope cut length = 1.5 × height — end terminations and tensioning allowance included.
How Many Levels
The user chooses the number of levels; the table gives the minimum. Three levels may be fitted on a five-metre system as well.
| Mast Top Height H₁ | Minimum Number of Levels |
|---|---|
| Up to 5 m | 1 level |
| 5–10 m | 2 levels |
| 10–15 m | 3 levels |
Stakes and Anchors
A drive angle within 5–15° causes no loss of capacity; at 30° the capacity drops by 23%. In group staking, the spacing between stakes may not be less than one third of the embedment depth.
Stake Pull-Out Capacity — Ø25 mm stake, vertical, 45° pull, rope ≤50 mm off ground
| Soil | Penetration per Blow, mm | 610 mm Embedment, kN | 915 mm Embedment, kN |
|---|---|---|---|
| Very hard / very dense | < 5 | 6.0 | 11.1 |
| Hard / dense | 5 – 13 | 3.8 | 7.1 |
| Stiff / medium dense | 13 – 38 | 1.9 | 3.6 |
| Medium | 38 – 76 | 0.96 | 1.8 |
| Soft / loose | 76 – 152 | 0.48 | 0.89 |
| Very soft / very loose | > 152 | 0.24 | 0.44 |
Pull Test — One Stake on Every Line
- Drive the stake at 5–15° from vertical.
- Pull in the rope direction with the come-along, through a crane scale or load cell, in steps up to the test load.
- If there is visible movement, drive the stake deeper, switch to group staking or move the point.
- Write the measured value on the installation record.
Test load = twice the rope force given on the installation record. With no record, apply at least 1.5 kN (≈150 kgf) and write the measured value on the record.
Ground That Will Not Take a Stake
| Condition | Solution |
|---|---|
| Asphalt, concrete | Anchor bolt, or a ballast block — attach the rope at the block's bottom edge |
| Rock | Expanding wedge rock anchor |
| Frozen ground | Drill, do not drive. A driven stake will not enter frozen gravel |
| Soft, saturated ground | Duckbill or helical screw anchor |
Rope, Pre-Tension and Installation Sequence
Rope. Use non-conductive rope so the antenna radiation pattern is not disturbed; polyester is the best-balanced choice in the field. Fit a thimble at every loop and a stainless rope clip at every termination.
Pre-tension. The value is given on the installation record. Tension opposing ropes equally; with four guys, a plumb mast does not prove that the tensions are equal — measure the opposing pairs separately. Over-tensioning reduces the load capacity of the mast.
The sequence is written for a single operator. All guys are connected with the mast retracted; the mast is then extended with the guys attached.
Set up the tripod, spread the legs equally and bring the top plate level with a spirit level.
Mark the azimuth lines — four lines, 90° apart. If the prevailing wind direction is known, set one line into it. Check that the lines clear the tripod legs and the operator walkway.
Calculate the level heights: divide the mast height by the number of levels. The stake radius equals the height; start the tape at the mast axis and mark points R₃, R₂ and R₁ on every line.
Drive the stakes — 5–15° from vertical, leaning away from the pull. Pull-test one stake on every line.
Fit the guy collars. The Level 1 collar goes immediately below the payload adapter.
Lay out the ropes and tie each rope to its own stake. Leave the tensioners fully open; check that no rope is fouled on another rope or on a tripod leg.
Extend the mast from the bottom section upwards; confirm by ear that the lock engages on every section. Take up the rope slack by hand, do not tension.
Tension from the bottom up: Level 3 first, then Level 2, Level 1 last. Tension opposing ropes in turn, in equal steps.
Re-tension. Tensioning an upper level slackens the ones below it; repeat step 8 once more.
Plumb the mast. Check it in two perpendicular planes with a plumb bob or spirit level.
Lock and record. Secure the tensioners and fill in the installation record.
Acceptance Checklist
Once the mast is plumb and before the system is handed over, verify each of the nine items below in turn. If any single item fails, the installation is not complete.
Level height: calculated value ±100 mm
Stake radius: within ±3% of the chosen design value
Guy angle 39°–50° (56° maximum on a constrained site)
Azimuth separation 90° ± 5°
Azimuth difference between levels: 0°
Mast plumb 1/400 — 25 mm over 10 m
Pull test: no movement at the test load
Rope pre-tension: within ±5% of target
Thimble and stainless rope clip at every loop
- Levels are never rotated relative to one another. All levels use the same azimuth lines.
- The levels on one line are never gathered on a single stake — the load on that stake multiplies by the number of levels and pulls it out of the ground.
- Ropes are never over-tensioned. Over-tensioning reduces the load capacity of the mast.
- Group stakes are never driven one behind the other; they are set in a row perpendicular to the pull.
Check the stake heads by hand every day; drive any that has loosened, or move it. After rainfall stake capacity is halved — repeat the pull test. Synthetic rope beds in over the first few days; check the tension every 3–7 days. Pre-tension is defined at the temperature of assembly — readjust it whenever the temperature changes by more than ±20 °C. After high wind, hail or snow loading, fully inspect the stakes, the rope terminations and the plumb of the mast.
Installation Record
Fill this in at every installation; one copy stays with the system. The pre-tension and test-load values are read from this record.
Level Heights and Radii — as measured
| Level | Collar Height h, m | Stake Radius R, m | Guy Angle, ° |
|---|---|---|---|
| Level 1 | |||
| Level 2 | |||
| Level 3 |
Stakes and Pull Test — per line
| Line | Azimuth, ° | Soil Class | Embedment Depth, mm | Test Load, kN | Result |
|---|---|---|---|---|---|
| Line A | |||||
| Line B | |||||
| Line C | |||||
| Line D |
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