Figure 11, Recommended mast length on top of a building, Warning – Vaisala WXT520 User Manual
Page 35: Caution
Chapter 4 _______________________________________________________________ Installation
VAISALA_______________________________________________________________________ 33
0712-009
Figure 11
Recommended Mast Length on Top of a Building
The recommended minimum length (marked with the letter h in
) for the mast that is installed on top of a building is 1.5
times the height of the building (H). When the diagonal (W) is less than
the height (H), the minimum length of the mast is 1.5 W.
WARNING
To protect personnel (and the device), a lightning rod should be
installed with the tip at least one meter above WXT520. The rod must
be properly grounded, compliant with all applicable local safety
regulations.
CAUTION
Installations on top of high buildings or masts and in sites on open
grounds are vulnerable to lightning strikes. A nearby lightning strike
may induce a high-voltage surge not tolerable by the internal surge
suppressors of the instrument.
Additional protection is needed in regions with frequent, severe
thunderstorms, especially when long line cables (> 30m) are used.
Vaisala recommends using a surge protectors such as the WSP150 and
WSP152 in all sites where there is an elevated risk of lightning strike.