SkyWrap is designed to withstand the aggressive environment encountered on overhead lines. The cable and accessories are resistant to lightning, fault current, electric field, vibration, ice, sunlight, rain, pollution and some designs are available for areas at risk of shotgun damage. The operating temperature range of SkyWrap cable is -40 - +85°C (-40 - +185°F). SkyWrap can be installed just about anywhere.

No, Lightning will never ‘strike’ SkyWrap because the lightning will ground itself directly on the host earth-wire (ground-wire) rather than passing through the dielectric material of SkyWrap. Although large amounts of heat can be generated in the earth-wire by a lightning strike, thermal transfer between the earth-wire and SkyWrap is minimal because of the small contact area. Testing has shown SkyWrap remains undamaged following a lightning strike with enough energy to melt 4 strands in an ACSR conductor.

No, SkyWrap is not subject to dry-band arcing or tracking and unaffected by the electric fields found on overhead transmission lines. Unlike ADSS, SkyWrap is in constant contact with its host earth-wire (ground-wire) or phase conductor along its entire length. This arrangement does not allow electric charge to build up on the dielectric cable and there is nothing to drive currents across the surface of the cable.

Where SkyWrap leaves the protection of an energised host phase conductor - for example to travel down the tower leg to a joint box - it is protected by a Phase to Ground (PTG) insulator that is designed to withstand the electric field environment. A PTG insulator is required if the earth-wire is insulated from the tower structure but not necessary when the host is an earth-wire at the same potential as the tower structure.

SkyWrap can induce corona discharge on phase conductors above approximately 160kV and therefore AFL does not recommend that SkyWrap is installed on phase conductors above 150kV.

SkyWrap remains unaffected by ice build-up on overhead line conductors.

Experience has shown that initially ice does build up quickly on the overhead conductor or earth-wire (ground-wire) which is equipped with SkyWrap. However, once the layer of ice fully covers the SkyWrap cable, the subsequent rate of build is the same as a non-wrapped conductor. SkyWrap does not cause any gross irregularities in the build-up of ice and therefore does not lead to wind-induced problems or mechanical instabilities in the ice layer.

No, the helical wrapping of SkyWrap cable disturbs laminar airflow over a conductor or earth-wire (ground-wire) in the open span of an overhead line. This can actually reduce the tendency for aeolian vibration to develop and may also prevent aerodynamic lift.

No, the SkyWrap installation equipment wraps the SkyWrap cable along the host conductor or earth-wire (ground-wire) under constant and controlled tension at a pitch length of about 900mm (3ft). It is the accurate control of installation tension that ensures the SkyWrap cable remains in contact with the host throughout the operating envelop of the overhead line – allowing for thermal expansion and contraction of the host, and it’s stretching due to ice and wind loads.

SkyWrap has a design life of 30 years and recent checks on some of the oldest installations have shown it to have suffered no measurable deterioration after more than 20 years in service. The oldest known SkyWrap installation still in service was installed in 1987.

Normal line maintenance can still be carried out effectively with SkyWrap installed. AFL has developed strategies to introduce slack into the SkyWrap cable to enable it to be moved aside from the conductor while repairs are carried out. The SkyWrap cable does not need to be cut or replaced and will continue to carry traffic throughout the maintenance procedure.

AFL has a range of tried and tested SkyWrap repair methods and is able to provide assistance and advice on the best solution for a particular scenario. Typically it is necessary to remove the damaged span of SkyWrap using a specially developed AFL recovery trolley, then install a new span of cable, and a new splice box.

SkyWrap is very reliable and requires very little maintenance during its life. However, where a customer requires the security of long term maintenance support, AFL offers a range of packages tailored to the size and type of SkyWrap link or network and the needs of the customer.

Support packages typically range from a guaranteed service response, including long term lease of specialist installation equipment with support from AFL Engineers to a simple spares stockholding arrangement. Condition assessment packages can be offered to provide regular reports on the condition of a SkyWrap link.

Yes, SkyWrap can easily be removed using equipment provided by AFL. A special device is attached to the front of an installation tug, which moves along the host earth-wire (ground-wire) or phase conductor collecting the cable in front of the tug in loops. At the far end of the span, the cable loops are cut off and fall to the ground. Any clamps and fittings attached to towers, poles and conductors are unbolted and removed. The process leaves the overhead line completely clean and unmodified by the SkyWrap installation and removal.

A single SkyWrap cable carries a maximum of 72 fibres. Two cables can be installed on a single host conductor bringing the fibre capacity up to 144 fibres per conductor or earth-wire (ground-wire).

Over 25,000km of SkyWrap has been installed in 40 different countries in the last 30 years (including more than 2,500km (1,500 miles) in the United States and Canada). Some projects have included large communications initiatives to install national networks such as ESB in Ireland (1,300km) and RTE in France (3,500km).

SkyWrap has been approved by many national electricity companies around the world and follows various international standards such as IEEE 1594-2008, IEC60794-4 and CIGRE (45,106,131,132,133). For a full list of references or qualifications contact AFL on sales@afl-europe.com

SkyWrap meets or exceeds the requirements of IEEE 1594 and IEC60794-4.

SkyWrap and ADSS are not strictly comparable – they are different technologies and are used in different circumstances. SkyWrap tends to be used in situations where ADSS is unsuited to the application. This would include:

•	Towers or poles unable to support the extra load of ADSS cable (especially under ice and wind loads)
•	Insufficient ground clearance under the line to allow ADSS to be installed in a low electric space potential regime
•	When ADSS would clash with other overhead conductors
•	Where there is a risk of crop fires/bush fires under the line
•	Where there is a risk of theft or vandalism to ADSS cables
•	When the local environment has high levels of pollution
•	When the line is close to the sea (within 20km / 12 miles)
•	Where the line is in a region with low annual rainfall, especially when there are long dry periods and occasional episodes of mist or fog
•	When the overhead line includes spans longer than 600m (2,000ft), especially in high wind areas
•	Access to the line is difficult, for example in mountainous, forested or water-logged terrain; in urban areas, or where there are high value crops, or in nature reservations or on military grounds.
•	The operating voltage of the overhead line is too high to allow the use of ADSS
•	When planning consents for additional aerial cable cannot be obtained

SkyWrap and OPGW are not strictly comparable – they are different technologies and are used in different circumstances. SkyWrap tends to be used in situations where OPGW is unsuited to the application. This would include:

•	When high network build speeds are required
•	When the cost of replacing an existing earth-wire (ground-wire) with OPGW is too high
•	When the disruption to electricity supply services and to the local environment is too great to allow installation of OPGW
•	Access to the line is difficult, for example in mountainous, forested or water-logged terrain; in urban areas, or where there are high value crops, or in nature reservations or on military grounds.
•	The overhead does not allow for an earth-wire – SkyWrap can be installed on a phase conductor