Underground Services Colours UK (And What They Mean)

We all use services, gas, electricity, water, communications, etc. Across the UK, we are connected to the services that power our homes and businesses and take our waste away.

And many of these services are laid underground. Hidden away and out of sight.

Out of sight, out of mind.

But what about when you need to dig?

If you ever need to dig up the ground, or excavate land, assume that services could be present. Before you dig yourself a hole (literally!), you need to know what services are in the ground, and where they are.

In an ideal world, finding underground services would never come as a shock. You would have a survey and a map of the exact location of all the underground services pinpointed to the exact location and depth.

And once exposed, services would be easily identified by the national colour coding system.

But this isn't an ideal world, and working underground is often more difficult than planned. Service maps are often not to scale and are just a rough guide as to where services are hidden. A wide variety of materials and colours have been used for services over the years, making identification difficult.

So you might come across underground services during groundwork. And if underground services are uncovered on your site, it is important to correctly identify the type of service so you can deal with it safely.

Failing to work safely around underground services can be deadly.

A construction company paid £210 000 in fines and costs after an employee died in an explosion following damage to an 11 000-volt live cable within an excavation. The worker suffered burns over 60% of his body while he and other workers were using breakers and a shovel within the excavation. He died of his injuries 13 days later. The company had not informed workers that there were live cables in the excavation and failed to put adequate measures in place to prevent them being damaged.

Locating Underground Services

Locating services isn't just important to avoid damaging the service. But to avoid damaging - or even killing - yourself. You need to know what services are where. And, if they are dead or live.

Locating underground services is usually a three-step process.

1. Desktop study: Requestion information from the client and service drawings from utility providers, to give you an idea of the type and location of services located on the site.
2. Site Investigation: This would usually involve a physical site inspection, looking for signs of services (e.g. manhole covers, telecoms boxes etc). The survey would use detection tools to get a more accurate idea of service locations.
3. Physical Identification: Using trial holes and tracing devices to get an exact location, depth and identity of services.

You should have a good idea from utility services searches and non-intrusive site surveys as to the location and type of services you are likely to come across on your site.

However, not all records are up to date and it can be difficult to determine the exact type of service from non-intrusive surveys.

Sometimes, it is not until the services are exposed on the site - after an intrusive site investigation, with trial holes and careful excavation work - that they can be identified.

UK underground service colours

Surely, once the services have been exposed during the physical identification they can easily be identified?

Not always.

Even at this stage, it can be difficult to determine the exact type and status of service. Modern services tend to follow a national colour coding system:

Black

Black Cables

• Electricity (High Voltage - HV)
• Electricity (Low Voltage - LV)
• Telecommunications
• Street lighting

Black Pipes

• Oil/fuel pipelines
• Water

Black Ducts

• Electricity (High Voltage - HV)
• Electricity (Low Voltage - LV)
• Sewerage
• Street lighting
• Communications

Red

Red Cables

• Electricity (High Voltage - HV)
• Electricity (Low Voltage - LV)

Red Ducts

• Electricity (High Voltage - HV)
• Electricity (Low Voltage - LV)

Yellow

Yellow Pipes

• Gas

Yellow Ducts

• Gas

Blue

Blue Pipes

• Water

Blue Ducts

• Water

Grey

Grey Cables

• Telecommunications
• Street lighting

Grey Pipes

• Water

Grey Ducts

• Water
• Telecommunications

Orange

Orange Cables

• Traffic control

Orange Ducts

• Traffic control
• Road lighting

Purple

Purple Cables

• Road lighting

Purple Ducts

• Road lighting
• Communications
• Communications Power
• Telecommunications

Green

Green Ducts

• Telecommunications

White

White Ducts

• Telecommunications

UK underground services colours infographic ⬇️

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These guidelines describe utility industry practice. However, it should not be assumed that all apparatus will conform to the recommendations for positioning and colour coding contained in this publication.

While modern services should conform to this system, older services can be more difficult to identify as a wide variety of colours and materials have been used in the past that didn't always conform to any particular system.

• ⚠️ Some colours may not be clear under poor lighting or artificial lighting.
• ⚠️ Underground services may also be hidden in protective ducts, and ducts could include any service type, making it difficult to identify the services.
• ⚠️ Some services could be covered in black plastic. These services can include water pipes, fuel, electricity cables and telecommunication cables. If black plastic is found always assume the service is a live electricity cable.
• ⚠️ Water pipes can be made of iron or steel and can appear very similar to gas pipes. In the interest of safety, such pipes should be assumed to be gas.

Identifying underground services

The identification of services should usually follow a system. Firstly, service records are gathered. A site survey scan should then confirm the location of the services identified within the plans. Trial holes are then dug to confirm locations and further safe digging is used to expose services as required.

However, work underground is rarely straightforward and at any stage in the above process, additional unknown services (live or dead) may appear on the radar as you scan the site.

If you are unsure about any services on your site, always assume the service is live electricity cable or gas pipe until otherwise confirmed. After all, it’s better to be safe than sorry.

Once you have identified services, they should be carefully exposed, supported and marked. Marking should be carried out on-site, and on plans.

• ⚠️ Always assume services are live unless you know otherwise.
• ⚠️ Be aware the status of services can change. Isolated services may become live again during a project, so always check and get confirmation from the service provider.

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Any work that involves digging or disturbing the ground should consider the risk of underground services. Never go into the ground unprepared. Before work starts on your site, service records should be checked and an initial assessment of the likelihood and location of services carried out.

Raise awareness of the risks with the underground services toolbox talk, and make sure your team know how to dig safely.