A-2
WaveNet Link AX Installation and Operations Manual
Protection Arrangements
The purpose of any protection arrangement should be to provide a suitable path to ground for
the lightning current, to ensure adequate bonding between structures and all metalwork on the
site and the common grounding system in order to reduce the side flashing, and to attempt to
prevent the entry of flashes or surges into the building.
The resistance to ground should be kept to a minimum and a value of less than 10-ohms is
recommended. The most important feature is that the system should ideally be at equal
potential across the entire site.
Certain authorities and service providers have their own particular practices which have to be
followed where applicable.
Arrangements will vary considerably from very simple sites to complicated sites with multiple
buildings, antenna support structures and associated equipment, and may involve integration
with existing systems. Such systems may require upgrading.
Lightning conductors
Down conductors, bonding interconnections, ground rings and radial tapes should be of
uninsulated 000 AWG copper cable or solid copper tape with a minimum cross section of 25 x
3 mm with all connections protected by non reactive paste.
Protected test points should be included if appropriate, and sacrificial ground lugs should be
clearly marked and easily accessible for periodic inspection.
Grounding of antenna support structures
A structure will generally act as its own lightning conductor and therefore will not require an
additional conductor from the top to the base. A lightning rod may be required to extend the zone
of protection to protect equipment mounted on the top of the structure. The lightning rod should
extend 2.5-meters above the highest equipment.
Ground mounted support structures should be connected at their base to a ground ring via
sacrificial ground lugs. Towers should have a connection from each leg.
A ground ring should consist of copper cable or solid copper tape with ground rods equally
spaced at 2-meter intervals around the base of the structure as close to it as possible, buried
approximately 0.6-meters deep where soil conditions allow. An alternative method using radials
rather than rings is detailed in “The ‘Grounds’ for Lightning and EMP Protection”, second
edition, published by PolyPhaser Corporation.
The ground ring should be connected to the main building ground by the most direct route,
buried as appropriate.
Roof mounted structures should be connected to the main building ground by the most direct
route using sacrificial lugs and copper cable or tape as appropriate. Tower guy wires should be
directly bonded at their lowest point to a suitable ground electrode or connected to the site
ground by the most direct route.
