Leica GM30 User Manual page 15

Down conductor
system
Grounding
Equipotentiali-
sation
Structural
separation in a
cabinet
GR30/GM30/GR50, Safety Directions
A down conductor system consists of a bonding network that covers the outer face
of a structure, for example building.
In a steel-reinforced concrete structure, the reinforcement of the outer walls can be
used as natural components.
Structures made of insulating material, for example wood or bricks, need an extra
bonding network as down conductor system.
As part of the external LPS, an earth termination system for grounding must address
low earth impedance.
Suitable for grounding are poles or depths/plate/ring earth counterpoises.
Disadvantages
• Corrosions depending on the soil conditions
• Damage due to excavation
Corrective measure
Use a foundation grounding rod. Such a rod is required for electric facilities in and at
structures, for example building, pillar or mast.
The foundation grounding rod is built into the concrete foundation of the structure.
Any incoming connection into a building that can transfer an electrical potential from
outside to inside must be protected against electrical discharge.
Recommendation
Deploy an EBB which is properly connected to the grounding system at the building
and/or cabinet entry point.
Part
Incoming connection into a building
Electrical discharge
Case
A cabinet box is used to protect the receiver and electronic against environmental
impacts.
Recommendation
Use a structural separation with a metal partition panel within the cabinet.
Purpose of a structural separation
• Separation of lightning protected and not protected part of the cabinet
• Avoiding crossed cables originating from the lightning protected and not
protected part of the cabinet
• Attenuation of transient and magnetic induced fields
Example
Water, gas, communication, data or
power line
Lightning surge
15