The Ultimate Guide to Stokbord Cable Covers: Heavy-Duty Protection for LV, MV & HV Networks

Published 06 Feb 2026

The Complete Guide to Stokbord Sheets & Cable Covers

For utility contractors and civil engineers, the risk of “striking” buried infrastructure is a daily operational hazard. Whether it’s an 11kV distribution line or a 132kV transmission cable, the consequences of accidental damage are severe, ranging from costly power outages to life-threatening injuries.

Enter Stokbord, the industry-standard solution for heavy-duty underground cable protection.

While Stokbord is widely known as a versatile recycled plastic sheet, in the utilities sector, it serves a specific, critical purpose: providing a high-impact, shatter-proof barrier over MV (Medium Voltage) and HV (High Voltage) cables.

In this guide, we explore why Stokbord has largely replaced concrete and tile tapes, the specifications you need to know (including ENA TS 12-23) and how to choose the right protection for your project available here at Thorne & Derrick.

What is Stokbord?

Stokbord is a heavy-duty protection board manufactured from 100% recycled polyethylene. It is chemically inert, rot-proof, and exceptionally tough.

In the context of power distribution, Stokbord is used as a mechanical barrier installed in the trench directly above underground cables. Its primary job is to withstand the impact of hand tools (like spades) and offer significant resistance to mechanical excavators, alerting the operator to the presence of a cable before damage occurs.

Key Characteristics:

• High Impact Resistance: Unlike concrete, which can crack or shatter, Stokbord absorbs energy and does not splinter.

• High Visibility: Typically supplied with a red background and a yellow “Caution Electric Cable Below” strip, offering an unmistakable visual warning.

• Lightweight: A single person can easily handle Stokbord sheets, significantly reducing manual handling risks compared to heavy concrete tiles.

• DNO Approved: It is the preferred protection material for most UK Distribution Network Operators (DNOs), including UKPN, ENW, and SSE.

Which Stokbord Product Do You Need?

At Thorne & Derrick, we stock the full range of Centriforce Stokbord solutions, catering to voltages from 11kV up to 400kV.

1. Stokbord Cable Covers (The Standard Tile)

This is the traditional format rigid sheets (typically 1 metre in length) that are laid over the cable and interlinked. They are ideal for protecting high-voltage connections where a robust physical barrier is required.

• Best for: 33kV, 66kV, and 132kV installations.

• Common Sizes:

  • Stokbord 1000mm x 152mm – Often used for smaller duct widths or single cables.

  • Stokbord 1000mm x 244mm – The industry standard for 33kV cable protection.

  • Stokbord 1000mm x 300mm – Wider coverage for larger trenches.

• Specifications: Our stock meets ENA TS 12-23 (Class 1 & 2) and National Grid TS 3.05.07 requirements.

2. Stokbord Drum (The Safety Revolution)

The Stokbord Drum is a game-changer for site safety. Instead of individual tiles, the protection is supplied as a continuous strip on a reel.

• Safety Benefit: It can be unrolled directly into the trench from the surface. This removes the need for operatives to enter the trench, eliminating confined space risks.

• Speed: Installation is up to 30x faster than laying individual concrete or plastic tiles.

Alternative: Tapetile

For lower voltage applications (typically 11kV or street lighting) where a heavy rigid board isn’t specified, Tapetile is the standard alternative. It is a flexible, recycled plastic roll that offers visual warning and moderate protection, bridging the gap between simple warning tape and heavy-duty Stokbord.

Technical Specifications & Approvals

When procuring cable protection, “compliance” is the keyword. Using non-compliant materials can lead to project rejection by the DNO.

ENA TS 12-23 Compliance

Most UK utilities require protection that adheres to Energy Network Association Technical Specification 12-23. Stokbord sheets undergo rigorous impact testing to ensure they can withstand strikes without penetrating the cable below.

• Class 1: Heavy-duty impact resistance (often required for 132kV+)

• Class 2: Standard impact resistance (common for 33kV)

Dimensions & Thickness

While dimensions vary by DNO specification, standard thickness usually ranges from 6mm to 12mm

• Length: 1000mm (standard tile)

• Connection: Tiles feature pre-drilled holes and are supplied with plastic jointing pegs to lock them together, preventing gaps from forming during backfilling

Installation Guide: Best Practices

Correct installation is just as important as the material itself. Always refer to your specific DNO’s engineering standards (e.g., UKPN ECS 02-0019), but the general procedure is as follows:

1. Bedding: The cable should be bedded in fine fill (sand) to prevent damage from stones.

2. Placement: Place the Stokbord cover centrally over the cable.

   • Standard Depth: Typically, the cover is placed 75mm to 150mm above the cable crown. This gap is crucial it ensures that if an excavator bucket hits the board, the force isn’t immediately transferred to the cable.

3. Jointing: Butt the 1-metre tiles together and insert the plastic peg through the pre-drilled holes to secure the joint.

4. Backfill: Carefully backfill over the covers.

5. Warning Tape: For High Voltage installations, an additional Underground Warning Tape is often placed 200-300mm above the Stokbord for an early visual warning.

Why Choose Stokbord Over Concrete?

We frequently get asked if concrete tiles are “better” because they feel heavier. In modern utility construction, the answer is almost always no.

Protect Your Infrastructures

At Thorne & Derrick, we are leading distributors of Centriforce products, supplying projects across the UK and internationally. Whether you are working on a wind farm connection requiring 132kV Type A covers or a local 11kV diversion using Tapetile, we have the stock and technical expertise to support you.