User's Guide Part 1

Lightning protection Chapter 2 Planning considerations
phn-0896_009v003
2-20
UNDER DEVELOPMENT
Feb 2010
The rolling sphere method
An imaginary sphere, typically 50 meters in radius, is rolled over the structure (Figure
2-6). Where the sphere rests against the ground and a strike termination device (such
as a finial or ground bar) all the space under the sphere is considered to be in the zone
of protection (Zone B). Similarly, where the sphere rests on two finials the space under
the sphere is considered in the zone of protection.
Grounding considerations
The PTP 600 Series ODU grounding point can be found on the bottom of the unit. The
ODU is supplied with an appropriate grounding lug.
The following protection requirements are mandatory:
• The ODU must be earthed
• Screened CAT 5e cable must be used
• Surge arrestors of type PTP-LPU must be installed at both the ODU and building
entry
• There must be an earth connection at building entry
The recommended standard components for protecting installations are listed in Site
i
nstallation diagrams on page 2-26.