User's Manual

I
NSTALLATION
S
AFETY
R
EGARDING
H
AZARD OF
S
HOCK
34
SpotCell 100, Release 1.0
For tall buildings (i.e. above 50m in height), lightening strikes are found
mainly on the protruding corners on the flat or slanted roofs instead of
the highest points. It has also been observed that the incidence of
multiple strikes on the exact same location is more commonly found in
tall buildings.
As indicated by the above paragraph, lightening protection can be
implemented by attaching a Franklin Rod on the points where
lightening strikes are most likely to occur.
There are two common types of Franklin Rods, a blunt tip version and a
sharp pointed version. A study conducted by the Langmuir Laboratory
of Atmospheric Research (USA) shows that the blunt tipped rod
performed better than the sharp pointed rod under natural lightning
conditions. After observing several of the above air terminals for seven
summer seasons, they discovered that only the blunt tipped rod with a
diameter of 19mm was struck by lightning.
Never attempt to install the DDU outdoors while a lightening storm is
in progress in your immediate or neighboring vicinity. The National
Lightening Institute says for every five seconds between the flash of
lightening and a thunderclap, the lightening is one mile away. If
lightening is within 3 miles (15 second count between flash and
thunder) of your location, stop work and seek shelter, avoiding solitary
tall trees as shelter.
If your hair stands on end or you feel tingling sensations, you are in
lightning's electric field. Immediately remove all metal objects and
crouch down with feet together and hands on knees.
C.2 Overhead Power Lines
While overhead power lines may appear to be insulated, they most likely
are not insulated. Contact to power lines by a mast or antennae can
seriously injure or kill a person.
Always thoroughly investigate your surroundings prior to installing
masts or antennas in an outdoor location, and never attempt this
without adequate lighting, as shadows and trees may obscure power
lines.