What Are Overhead Ground Wires?
An overhead ground wire is a metallic wire or stranded conductor installed above the phase conductors of a transmission line. Also known as an earth wire or shield wire, it helps intercept lightning strokes and carries lightning or fault current towards the tower grounding system. Its primary role is line protection rather than normal power transmission.
Ground wires are used on overhead transmission lines where lightning shielding, mechanical strength and fault-current performance must work with the tower and grounding design. They are applied in new line construction, ground-wire replacement and network upgrades, with the selected design matched to route conditions, spans and the required electrical duty.
Our range includes three main product families: GSW, ACS Ground Wire and OPGW. Together, they cover galvanized-steel ground wire, aluminium-clad steel ground wire and ground wire with integrated fibre-optic communications.
OPGW, or Optical Ground Wire, integrates optical fibres into an overhead ground wire. Its core difference from GSW and ACS Ground Wire is that it combines lightning shielding and grounding with communication channels for protection, control and data transmission.
How to Select an Overhead Ground Wire
The choice among GSW, ACS Ground Wire and OPGW depends on how the project balances material construction, electrical duty, mechanical loading, corrosion exposure and communication requirements. The table below compares these factors at product-family level.
| Comparison factor |
GSW |
ACS Ground Wire |
OPGW |
| Material & Coating |
Stranded steel wires protected by a zinc coating. The coating class and steel grade are selected to the applicable standard and project specification. |
Stranded aluminium-clad steel wires with an aluminium layer metallurgically bonded to the steel substrate. |
A metallic stranded ground-wire construction incorporating a protected optical unit; outer wire materials depend on the selected design. |
| Electrical Performance |
Provides a conductive path for lightning and fault current through the line grounding system. Electrical performance depends on strand size, steel grade and construction. |
Aluminium-clad steel construction provides a different electrical-resistance and fault-current performance profile from galvanized steel strand. |
Combines the electrical duty of a ground wire with optical signal transmission for protection, control and communications. |
| Mechanical Strength |
Steel construction provides the tensile capability required for conventional overhead shielding and mechanical duty. |
The steel substrate provides mechanical strength, while the complete construction is selected to balance strength, weight and electrical requirements. |
The self-supporting metallic structure is designed to carry line tension and environmental loading while protecting the optical fibres. |
| Corrosion Resistance |
The zinc coating protects the steel wires; coating class and environmental exposure should be considered together. |
Provides a different balance of mechanical strength, conductivity and corrosion performance through aluminium-clad steel construction. |
Corrosion performance depends on the outer wire materials, optical-unit protection, hardware compatibility and service environment. |
| Main Applications |
Conventional overhead ground wire or static wire for lightning shielding on transmission lines. |
Overhead ground wire where the project requires a combined balance of strength, electrical performance and corrosion behaviour. |
Transmission lines requiring lightning shielding and grounding together with fibre-optic communications. |
Selection Support: To identify the appropriate product family, share the line voltage, span and loading conditions, prospective fault-current data, grounding arrangement, corrosion environment and any optical requirements. Our team will compare these requirements and recommend whether GSW, ACS Ground Wire or OPGW is the appropriate starting point for detailed design.
Applications of Overhead Ground Wire and OPGW
Overhead ground wires and OPGW support new transmission-line construction, lightning-protection upgrades, ground-wire replacement and utility communication projects. The appropriate solution depends on whether the project requires conventional metallic shielding, an alternative material-performance balance, or combined grounding and fibre-optic communications.
Lightning protection for transmission lines
Use GSW where the project needs a conventional metallic ground wire for shielding and mechanical duty, with coating and strength selected for the line conditions.
Ground wire for exposed environments
Consider ACS Ground Wire where conductivity and corrosion protection need to be balanced with the mechanical role of the ground wire.
Grounding plus fibre-optic communications
Use OPGW when the transmission route must support lightning shielding and grounding together with protection, control or telecommunications channels.
New-build and retrofit projects
For new lines, ground-wire replacement or OPGW retrofit, we help review line duty, tower loading, fittings, installation constraints and the required documentation.
Overhead Ground Wire and OPGW Standards
OPGW projects commonly reference IEC 60794-4, IEC 60794-4-10 and IEEE 1138. These standards address the construction, optical, mechanical, electrical, environmental and testing requirements relevant to optical ground wire used on electric utility power lines.
Metallic ground wire projects may reference IEC 63248 and IEC 61089 for applicable wire materials and stranded conductor construction. ASTM A363 applies to zinc-coated steel overhead ground-wire strand, while ASTM A925 applies to zinc-5% aluminium-mischmetal alloy-coated steel overhead ground-wire strand.
Project Support
For support with ground-wire or OPGW selection, specifications or sizing, please contact our team with the line conditions, fault-current data, optical requirements and applicable project standard.
