Emerson Process Management ControlWave EFM 3808 - Manual (Page 281)

Section 4 - Lightning & Surge Page 4-3 S1400CW
modem has been interfaced to a ControlWave, ControlWave MICRO, ControlWave
EFM/GFC/XFC, ControlWaveLP, or ControlWaveEXP the possibility of damage due to a
lightning strike on power or telephone lines or to a radio antenna or the antenna’s tower
must be considered. It is recommended that the additional lightning protection
considerations listed below be followed for units installed in areas with a high possibility or
history of stroke activity.
Units interfaced to a modem: In series with the phone line (as far away as possible
from the equipment) - for indoor installations the lightning arrester should typically be
located at the point where the line enters the structure.
Units interfaced to a radio: Mount antenna discharge unit (lightning arrester) as
close as possible to where the lead in wire enters the structure. See Antenna Caution
below.
4.1.2 Antenna Caution
Each year hundreds of people are killed, mutilated, or receive severe permanent injuries
when attempting to install or remove an antenna or antenna lead. In many cases, the
victim was aware of the danger of electrocution but failed to take adequate steps to avoid
the hazard. For your safety, and for proper installation maintenance, please read and
follow the safety precautions that follow - they may save your life.
i When installing or servicing an antenna:
DO NOT use a metal ladder. DO NOT step onto or touch an antenna mast while power
is applied to an associated radio unless the radio is a low power (low current) type.
DO NOT work on a wet or windy day, especially during a thunderstorm or when there is
lightning or thunder in your area. Dress properly; shoes with rubber soles and heels,
rubber gloves, long sleeve shirt or jacket.
i The safe distance from power lines should be at least twice the height of the antenna
and mast combination.
i Antenna Grounding per National Electrical Code Instructions:
A. Use AWG 10 or 8 aluminum or AWG 1 copper-clad steel or bronze wire, or larger as
ground wires for both the mast and lead-in. Securely clamp the wire to the bottom of
the mast.
B. Secure lead-in wire from antenna to antenna discharge (lightning arrester) unit and
the mast ground wire to the structure (building, shed, etc.) with stand-off insulators
spaced from 4 feet (1.22 meters) to 6 feet (1.83 meters) apart.
C. Mount antenna discharge unit as close as possible to where the lead-in wire enters
the structure.
D. The hole drilled through the wall for the lead-in wire should be just large enough to
accommodate the cable. Before drilling this hole, make sure there are no wires or
pipes, etc. in the wall.
E. Push the cable through the hole and form a rain drip loop close to where the wire
enters the exterior of the structure.
F. Caulk around the lead-in wire (where it enters the structure) to keep out drafts.
G. Install lightning arresters (antenna discharge units). The grounding conductor
should be run in as straight a line as practicable from the antenna mast and/or the
antenna discharge units to grounding electrode(s).
H. Only connect the antenna cable to the radio after the mast has been properly
grounded and the lead-in cable has been properly connected to lightning arresters
which in turn have each been properly connected to a known good earth ground.