MicroMAX Hardware Installation User Guide
Page 79
Commercial in Confidence
UWB-D00068 Rev J
Level of
Protection
Flash density * Equipment placement
**
Installation accessibility
***
Landscape
3 High -
-
Hilly
2 Low
-
Good
Mountainous
3 Low
-
Poor
Mountainous
3 Medium -
-
Mountainous
3 High -
-
Mountainous
* Density (strikes per kilometer square per year)
o
Low = Less than 5
o
Medium = 5 – 14
o
High = more than 14
** Relative to ground level
*** Accessibility – cost/time affects replacement considerations
Recommended good practices:
¾
Air-terminal and grounded mast/tower.
¾
Proper
Bonding
¾
Proper
Grounding
17.1 Lightning Protection
This is to describe the known mitigation defenses in general terms for application to
telecommunications facilities. A hierarchy of recognized application methods should be applied
according to site realities. This matrix is depicted below:
Table 28 - Application matrix
Exterior location Interior Location People Safety Structure Safety
Air Terminals
Yes
No
No
Yes
Down Conductors
Yes
Yes
No
Yes
Bonding Yes
Yes
Yes
Yes
Grounding Yes
Yes
Yes
Yes
Surge Protection
Yes
Yes
Yes
Yes
17.1.1 Air Terminals
Lightning usually terminates on grounded objects sticking up in the air. This part of a lightning
protection system (LPS) is based upon the principles of Path of Least Impedance. On telecom
towers, ordinary sacrificial rods can protect sensitive antennae. In the main, the tower is the air
terminal. the height (“H”) of the Air Terminal tip above the highest element on the tower or pole,
typically the antenna, must be at least twice the distance (“2 x d”) between the outer surface of
the antenna and the tower or pole. This will ensure a "protection cone" of 45º around the tower or
pole. In areas of high lightning activity, the length (“H”) should be increased to up to 5 times the
distance. The Down Conductor must be installed straight and vertically in order to provide the
shortest and most direct path to earth. The formation of bends must be avoided.
We recommend that the Down-Conductor be at least 50 mm2 or AWG 0 in all cases.