Skill: Dig in Cables/Duct and Make Good with Tarmac, Pavers, and Gravel
Skill level: 2
Gate Mechanics
Learning Objective
Understand how to safely and professionally dig in duct or cable, and make good with the appropriate finish (tarmac, paving, gravel) to ensure functionality, safety, and a tidy final appearance. This is mainly for new mains cables. You may need a machine for longer runs.
1. Overview
Poorly installed cable runs can cause:
Trip hazards or vehicle damage
Damage to buried services
Water ingress into ducting
Customer complaints due to untidy finishes or delays
✅ Your aim is a clean, secure, and professional job that lasts — and doesn’t need fixing later.
2. Tools & Materials Required
CAT scanner
Insulated digging tools
Maybe trenching machine
Maybe mini digger
Ducting (usually 40mm or 63mm)
Electrical warning tape
Tarmac (20mm)
Concrete (for duct bedding)
Playpit sand (for paving)
Soft-faced mallet
Tarp or sheeting
Blowtorch (for softening tarmac)
Rake, broom, gloves, torch
3. Before You Start
Confirm cable/duct route with customer and co-workers (see other lesson)
Use a CAT scanner to avoid underground services.
Check weather forecast — avoid digging in heavy rain.
Plan where to put spoil — bring tarps or buckets.
Ensure correct tools and materials are on site (pavers, tarmac, sand, barriers).
Ask: Will access be needed over the trench soon?
Decide if a trencing machine, mini digger or manual excavation is most ecconimical. A trenching machine will not work at all well on anything other than clean soil, a mini digger is good for any ground but makes a big mess, hand digging is ok up to about 20m but 1-2 man days is the maximum before machine hire becomes a better option. Even if it costs a little more.
4. Procedure (Main Process)
A. Prepare and Dig
Confirm route, scan with CAT.
Mark dig line and check for obstructions.
Brush gravel back to one side far enough away not to mix with the spoil.
Cut and remove or roll up turf carefully if present.
Dig trench to required depth (typically 300–600mm).
Place spoil on tarps, not directly on surfaces.
Lay duct or cable, include warning tape 100mm above cable.
Keep min 50mm separation mains from data cables.
B. Backfill
Consider backfilling the same day or even as you go if appropriate. If you have a spare person and the ground is soft they can lay the cable, dig tape and back fill by hand behind you.
Use soft sand around cable or duct as needed.
Compact gently as you go to avoid later sinkage.
Leave room for finish layer.
Bulking up usually settles back down to it original volume after some time.
C. Reinstatement by Surface Type
Pavers: Ensure compacted base is level. Replace pavers, tapping gently with a soft mallet. Fill joints with playpit sand and sweep thoroughly.
Tarmac: Concrete around duct if required. Place and compact tarmac while warm. Use a blowtorch to soften cold tarmac for compaction or use tarmac that is preheated. Slightly overfill — it will settle.
Gravel: Rake back evenly. Compact sub-layer beneath if disturbed. Add matching gravel for a neat finish.
Turf: Place turf back over the trench, don't worry if it's standing a bit proud it will settle and patches of missing grass will recover quickly.
5. Best Practices
Photograph trenches and reinstatement for records.
Label duct routes in Clik/job notes.
Keep trench lines as short and direct as possible.
Use barriers/signs if trench must be left open temporarily.
Ensure reinstated finish matches surrounding area.
6. Common Mistakes to Avoid
🚫 Forgetting to CAT scan = service strike
🚫 Leaving spoil scattered or turf upturned
🚫 Failing to concrete around ducts = future subsidence
🚫 Laying pavers on poor base = loose/rocking finish
🚫 No warning tape = no future warning
🚫 Leaving surface below finish level = visible dip later
7. Safety References
Refer to:
SSOW-09: Safe Use of Cable Avoidance Tools
SSOW-01: General Site Safety
SSOW-04: Excavation and Groundwork Safety
before starting duct/cable digging works.