Have you ever wandered the aisles of your local hardware or plumbing supply store and boggled at the sheer amount of products available for home improvement? Row upon row of arcane looking items, each designed to fulfil a specific function far beyond the ken of the casual onlooker. Being an observant and slightly obsessive person, I’ve learned that even the most mundane thoughts can lead to interesting insights. I was unexpectedly reminded of that hardware store experience recently when I became curious about the different coloured ducting I’d noticed in a housing estate currently under construction near my home. I made it my mission to understand this obvious, yet cryptic cypher.

Underground Ducting

Image by srv007 via Flickr



Armed only with my trusty internet connection, laptop and an enquiring mind, I plunged into my quest for knowledge by first searching for pipe, conduit, coloured plastic tubing and even ‘giant spaghetti in trenches’. This circuitous maze soon led me to the term ‘ducting’ where I eventually struck gold. By following this thread I learned an abundance of diverse and obscure facts about the development and properties of polyethylene, the perils and pitfalls of underground cabling, standard ducting lengths, diameters, stress loads and much, much more regarding the amazingly interconnected world that is buried only inches beneath our feet.



With the ever increasing availability of more and more services and a growing awareness of visual pollution and environmental aesthetics, the logical place for services to be located is underground. Safety is also an important consideration, the common wisdom being that placing ducted cables underground better protects them from being severed by road accidents, adverse weather, fire and random animals. Keeping the cables and pipes out of sight means they cannot easily be cut, diverted or intentionally interfered with. Yet at the same time, hidden cable ducts also mean hidden risks to builders, council workers, trades people and service providers whom may encounter them in the course of an average work day through digging, drilling, excavation and road construction.



Polyethylene is used to manufacture underground ducting and is an ideal material because of its stability, versatility, durability and strength. Polyethylene does not become brittle with age nor exposure to adverse weather and thereby resists degradation. Placing cable ducts beneath soil, roads and concrete also requires that strict practices are observed in regards to underground drainage as well as anticipating potential ground movement, soil pressure and above ground activity. It is pointless to transfer services underground only to have them waterlogged, inaccessible for maintenance crews or confused for another type of service altogether and unwittingly interfered with.


To maintain safety and avoid confusion the need for colour coding becomes paramount. When it comes to identifying underground cabling, it seems that the United Kingdom useswhat is known as a convention, rather than any binding standards. Conventions develop over time and are generally agreed upon by various industry players rather than being enforced or standardised.



It was the brightly coloured cable that first drew me to seek out the meaning and difference of the various colours. I discovered that cable ducting comes in a range of colours which serve to specifically identify the nature of the service contained by the ducting. This in turn assists trades people and contractors to treat the ductingwith the requisite caution and care. When installing services it is vital to always make sure the correct colour channel is used.


The most common colours used in construction are:

  • BLACK – Electrical power supply
  • BLUE – The supply of potable water
  • YELLOW – Gas lines
  • GREEN – CCTV, Cable TV
  • GREY – Telecommunications such as phone lines and Internet connections
  • PURPLE – Is used for communication related to motorways
  • ORANGE – Denotes traffic signals and street lighting


As someone curious about the world around me I’m grateful for these small insights into the practices that keep modern life in motion. I now find it impossible to use electricity, telephones and the internet without giving a little thought and gratitude to the colourful world below that keeps us all connected.