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Protecting your Electric Cables with Underground Ducting

Underground electrical ducting is used to protect electrical cables such as the mains supply to your property, as well as other underground electrical cables laid as part of renovations and home improvements; for example, if you wished to run a power supply to a summer house or garden shed.


Ducting is necessary in order to keep the cables safe, preventing a whole range of hazards such as physical damage and environmental wear and tear on the cables themselves.

Damaged, exposed or otherwise unsafe electrical cables can of course pose a serious threat to health and safety. Any injuries, property damage or in a worst case scenario, fatalities that occur as the result of failing to use and correctly install the appropriate ducting is likely to be considered as criminal negligence or even manslaughter by the relevant authorities.

When self-digging a trench for the installation of mains electric cables, it is important to make contact with the relevant power network provider to ensure you meet their installation requirements of trench depth, width and ducting class and type. For example: Western Power Connections

However, getting things right and protecting yourself, your property and other people is not hugely complicated, once you get to grips with a few basics!

More about plastic underground ducting

Different types of cable installations require different types of ducting. High-voltage cables will be ducted through a red or black class 1 duct, your power network provider will specify the colour. Commercial and infrastructure projects will on most occasions require a black class 2 ENATS duct, while most renovations and home and garden upgrades involve only low voltage cables, which require black class 3 ducting. ENATS 12-24 class 3. EN61386-24 class 3.

Not only are these types of underground ducts designed specifically to stand up to the rigours of underground usage and the supply that passes through them, but the at-a-glance colour coding system used makes it easy for maintenance workers and power company officials to tell what they are dealing with if they need to access them! Black ducting for low-voltage use must be stamped with the legend “Electric Cable Duct” along the side of the pipe, to allow for easy identification.

Additionally, the use of belowground ducting should also incorporate signage in the form of warning tape stating “Caution Electric Cable Below" laid directly over the duct 240mm below the surface in gardens and paths, 100mm below roads and 650mm below in agriculture land. This will inform workmen who may need to dig or excavate in the area of the cables in the future.

According to Eon Central Networks, underground low voltage electrical cable ducts should be laid at a depth of at least 45cm from the surface, increasing to 75cm if being installed in a carriageway, and 100cm when in agricultural land that is not subject to deep ploughing. It is always good practice to follow the most direct available route possible in straight lines and according to the alignment of walls and footpaths, where relevant.

For the installation or upgrade of low-voltage underground cabling within a domestic setting, you should be sure to purchase the appropriate black ducting that is stamped with the notation “Electric Cable Duct.” Whilst other colours and types of ducts may be identical in virtually every way aside from their colour, only black ducting is authorised for use with low-voltage electric cables!

Plastic ducting for electrical low voltage cables comes in various forms and can be commonly found in twinwall & singlewall versions, both with a range of different diameters and lengths.

The diameter of the ducting that you choose is something that you should consider carefully too, as depending on the type of supply that you will be working with, different diameters are required. As a general rule, three-phase supplies will use 50/125mm ducting, while single-phase supplies require 32mm. Of course, you will need to check with your power network provider, as they will specify the duct size and class required.

Installing plastic underground ducting

Installing underground ducting safely and efficiently is not complicated to achieve, but it can be hard work! Before you even begin to dig, it is important to make sure that you have access to any schematics that you might need to help you to identify and avoid existing underground services, and that you are alert to the possibility of unknown or unmarked hazards that you might come across as well.

You will need to dig a trench of the appropriate depth and width as specified by your power network provider, after first laying out the path that you want your ducting to take along the side of the route, so that you can mark out your trench’s location and stick to the map, as it were!

The bottom of the trench should be covered with sand to protect the ducting against sharp edges, and then you’re ready to lay your ducts out in the trench itself. Once your ducts are all laid, connected and ready to go, don’t forget the importance of marking the land above them with the appropriate electrical indicator tape before you cover everything back over.

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