Everything you need to know about outdoor power cable

Installing cable outside? Discover which electrical cables are suitable for external use in our latest blog.

24/11/2021 - 01:00 AM

As working from home grows ever more popular, those with home working set ups are increasing their use of their electrical facilities. Because of this, it may be necessary to set up remote buildings to use as workshops or home offices. This would require electrical professionals to assess the requirements needed to power the outbuilding, new building or separate building, such as, what is the load, what installation method is best, and how to plan the cable route.

For this to happen, outdoor electrical cable will need to be installed in order to power the building’s electrical services. So, what cable should be used?

Cables designed for external use should be able to withstand the adverse conditions. The outer layer of the cable needs to be durable enough to protect the cable from mechanical damage, water, extreme variations of temperature, insect and rodent attacks, as well as UV exposure from sunlight. The electrical cable should also be protected during handling and installation. Cables for external use are heavy and unsuitable cable is likely to get damaged if they are mishandled or dragged around.

What kind of electric cables can be used outdoors?

Steel Wire Armoured (SWA) cable
Aluminium Wire Armour (AWA) cable

Steel Wire Armoured (SWA) cable is a power and auxiliary control cable, specially designed for use in mains supply electricity. It is used to distribute power in numerous outdoor and indoor applications such as underground systems, direct burial, cable networks, power networks, clipped direct and cable ducting. The steel wires are also galvanised to prevent failure due to rusting.

Depending on the application or purpose, the number of cores within the SWA cable can vary. Usually, SWA cables are constructed with class 2 stranded plain annealed copper wire conductors to comply with BS EN 60228. These are covered by an extruded layer of cross-linked polyethylene insulation. The insulated conductors are then ‘laid-up’ or helically wrapped together and a bedding layer extruded on top.

The electrical cable is then enclosed in a layer of armour to provide mechanical protection and completed with a PVC outer sheath which provides additional protection from daylight UV rays and water. For protection against artificial UV sources such as science projects, an additional barrier is needed. It is important to note that UV protection is an additional feature in SWA cables and is not a requirement in the BS 5467, BS 6724 or BS 7846.

These cables are often used for external applications because it features mechanical protection. Its armour is used to reduce the risk of damage to the cable while being installed and also by third parties after installation. SWA cables are rigid and heavy, which makes them very difficult to bend but also very robust and only increases their suitability for use underground or fixed to outdoor walls using cable cleats.

Aluminium wire armour is used instead of steel when a cable has only one core because aluminium is non-magnetic. A magnetic field is produced when an alternating electric current passes through a cable. The higher the current, the bigger the electric field, and this field will induce an alternating electric current in nearby metallic elements such as the steel wire, which could cause overheating and significantly affect the current carrying capacity of the cable.

What makes Prysmian outdoor cable stand out?

Our XLPE insulated, PVC sheathed SWA and AWA cables are manufactured in accordance with BS 5467.

Prysmian BS 5467 is a low voltage armoured power cable with XLPE insulation and mechanical protection provided by galvanised steel wire armour. The range comprises 1, 2, 3, 4, 5, 7,12, 19, 27, and 37 cores and is well suited to areas at risk of mechanical damage. BS 5467 3 core cables can be installed for outdoor applications and laid into cable ducts or underground cable trenches using the right cable pulling and laying equipment.

BS 5467 is currently the most calculated cable in our cable calculator tool CableApp where electrical professionals can select the best type of cables that are required for each type of project and installation, including outdoor cables. Learn more about CableApp here.

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