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RF Coaxial Lightning
& EMP Protection
Application Notes
M/A-COM, Inc.
North America:
Tel. (800) 366-2266
s
Asia/Pacific: Tel. +85 2 2111 8088
s
Europe: Tel. +44 (1344) 869 595
Fax (800) 618-8883
Fax +85 2 2111 8087
Fax +44 (1344) 300 020
14
Specifications Subject to Change Without Notice.
To ensure that proper, low level contact resistance is established between the LP device
and mounting wall, it is recommended that a minimum torque of 50 in/lbs / 5.65 n/m
be applied to tighten the connector mounting nut. A recommended minimum torque of
35 in/lbs / 3.95 n/m should also be applied for installation of replacement surge protector
capsules to ensure proper protection performance.
In order to ensure that resultant currents from lightning or EMP strikes do not interfere
with parallel transmission lines within protected electronic equipment, surge protector
devices must be installed with proper orientation. The surge protector side of the
device should be mounted in the unprotected side of the equipment while the
mounting nut is positioned internally in the protected area.
It is important when planning lightning protection, that the user can estimate the
potential number of direct strikes. This information may influence the type of device
selected or the requirement for routine maintenance checks. Significant attention must
be paid to the height of supporting structure as this, when related to the typical
number of thunderstorms in a particular region, allows us to estimate the probability of
a direct strike taking place. To assist our customers in this, the following table and
chart has been included in this note. This should enable lightning protection planners
to establish the likelihood of direct strikes across a network anywhere in the world.
Number of Thunderstorm
hmax/m
Days per year
10%
20%
50%
05
28
39
61
10
18
26
40
15
14
20
31
20
12
17
26
30
9.4
13
20
40
7.9
11
17
50
6.9
9.5
15
70
5.6
8.0
12
90
4.8
7.0
10.6
130
3.9
5.5
8.5
150
3.5
5.0
7.7
180
3.1
4.4
6.9
Recommended
Mounting Techniques
Surge Protector
Mounting Techniques
Selecting your RF
Coaxial Lightning
Protection Device
Lightning Protection
Planning
Table 1: Maximum height of supporting building for a given number of thunderstorm days (when
hmax is exceeded, probability of direct strike to supporting building within 15 years is greater than
10% for hmax values given in second column, 20% for hmax values given in third column and
50% for hmax values given in the fourth column).