Everything you should know about underground ducting

Almost every building makes use of utilities and services which rely on cables and pipework to carry them to and from the property. Ducting is often used when these services are buried underground to protect both human life and the cables too. Find out more below.

Table of Contents

1. Why use underground ducting?

2. Things to remember when installing underground ducting

3. How to check your underground ducting

4. What does the law say about underground cables?

Why use underground ducting?

Underground ducting keeps people safe and protects essential utilities that many buildings, both domestic and commercial, rely on for smooth running. Services like electricity, water, gas, internet and phone lines can all be buried underground so it’s essential that they are protected.

Underground cables can’t be damaged as easily

Leaving cables and pipework on the surface means they can be easily broken, damaged or even purposefully tampered with. Over many years, pipes and cables are subject to weathering too so burying them in a protective duct will slow this process.

Underground cables can’t cause damage as easily

By burying cables, especially electrical and gas cables, it minimizes the risk to humans and animals by limiting the chance that any cables will be purposefully or accidentally touched. The ducting itself that wraps around the cable provides insulation from electric shocks and other potentially harmful events too. Below shows street lighting and traffic cables alongside mains domestic electric cables.


Burying cables is a much neater solution than leaving them on the surface

There are millions of miles of cables in the UK so leaving them on the surface would be practically impossible. Burying cables is a neat solution especially in dense areas where perhaps 1000 new homes are built, and each home must be connected via cable to water, electric, gas, internet and communication lines at minimum.

Underground cables protect our water sources

Cables at both the surface and underground can leak. That’s the unfortunate truth! Burying cables underground is a better way to ensure that any substances leaking from cables doesn’t immediately affect water sources. The ducting contains the leak and prevents contamination.

Things to remember when installing underground ducting

When installing underground ducting for cabling, there are a few key things to remember that will eventually become second nature to a regular installer.

Make sure you have the correct colour ducting

underground-coloursThe colour of underground ducts isn’t just for style! Each colour represents which service or utility is in the ducting so installers, excavators and anyone else knows what they’re dealing with. It’s a reliable way of protecting people and pipework/cables if it’s done correctly so it’s wise to know the universal underground cable colour code for the UK. Click the table to the right to see the colour codes.

Use common sense when choosing an installation area

It makes sense to first try to run underground ducting beneath a path or somewhere similar. Property boundaries could be a good idea for this dependent on the service and who owns the bordering land. If the same utility company is responsible for both plots for example, it doesn’t matter if the cable is buried on the boundary. Don’t forget to use a locating device and up-to-date plan to mark out where these cables are installed.

Double check legal excavation depths

There is legislation that dictates the minimum burial depth for some underground cables. This is typically dependent on what the cable is and what you can reasonably expect that land to be used for for the lifespan of the cable. For example, if land could reasonably be used as farm land in the next 5 years, it’s advisable you use farm land minimum depths.


How to check your underground ducting

Typically, you have to dig down and excavate a large portion of soil to inspect underground ducting so before you do this why not consider any conceivable threats to the ducting?

Think about issues you already know about

Is the soil in the local area known to have chemicals in it? Is it corrosive? Was there a recent storm or a flood that could have moved or damaged the ducting? Think back to recent events which could reasonably have caused faster corrosion or damage.

Physically inspect the ducting

After considering issues in the local area it’s time to inspect the ducting. Switch off the utilities and leave some time between when they were switched off to when you inspect them to ensure there’s no gas, electricity etc. still live in the cabling.

Avoid touching the ducting and cables

Inspecting the cables can be done visually by assessing the condition without touching. Visually inspect for fraying, obvious cracks or breakages, disruption in connections and any thinning of material.

What does the law say about underground cables?

A reliable resource for finding information pertaining to underground cables and the laws around them is Street Works UK. This government site has 6 volumes of publications that each contain specific information dependent on the location or use of the underground cables. For example, Volume 2 offers guidelines around positioning underground utilities in new developments and Volume 3 contains information regarding the management of third-party ducting.

HSE offers more information on excavation and underground services including how you should take care when digging in any area and how to use a locating device to compare plans to what’s in the ground. Some professionals advise that plans should be used as a starting point to find underground cables and they shouldn’t be taken as gospel.

Please remember: it’s illegal to use or continue to use an underground cable and any attached equipment if you are aware that the cabling does not comply with regulations relating to excavation depth of underground cables and protective screens for live cables that aren’t earthed. Find more on the HSE website.


Get to grips with underground ducting and get in touch with our customer service advisors on 01752 692 221 for advice and guidance on your project.

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