INSTALLATION OF MONITORING STATIONS - Wind Resource Assessment: A Practical Guide to Developing a Wind Project - page 63

• follow all safety guidelines provided by the tower and equipment manufacturer;
• use common sense during the installation process. For example, if there is light-
ning activity, postpone work until the danger has passed;
• have the proper safety equipment, including hard hats, protective gloves, eye
protection, proper shoes or boots, vests for greater visibility, a first aid kit, and,
if tower climbing is required, certified climbing harnesses and lanyards;
• maintain adequate hydration, use sunscreen, and wear appropriate cold-weather
clothes where necessary;
• be trained in first aid and CPR (cardiopulmonary resuscitation);
• exercise caution when driving off-road to avoid accidents;
• make sure the base of the tower is at least 1.5 tower heights away from overhead
power lines;

be aware of any equipment on the tower that may be electrically live, and
if possible,

•

turn off AC power at the tower base before working on the

tower;

before digging or installing earth anchors or rods, contact the local underground
facilities protection organization to identify and mark any existing hazards (e.g.,
buried electric or gas lines);

•

inspect any existing tower, anchors, and guy cables before conducting new work;

•

tension the guy wires according to the tower manufacturer's specifications;

•

have at least two tower climbers, both trained in tower rescues, for lattice tower
installations;

•

notify local airfields when new towers are erected to ensure that the pilots are
aware of the new structure, and ensure the towers are marked in accordance with
local guidelines.

•

5.5 DETERMINATION OF TRUE NORTH

Knowing the direction of true north is essential for interpreting direction data and
is also useful during the tower layout and installation. In a surprising number of
monitoring programs, direction vanes and anemometers are not oriented in the cor-
rect, documented direction. This can cause significant errors in wind flow and wake
modeling and result in a poor turbine layout.
Often, directional errors arise because of confusion between magnetic and true
north. Magnetic north is the direction in which the north end of a compass needle
points; true north is the direction along the local line of longitude to the north pole.
Sometimes, the correction from magnetic north to true north is applied wrongly, and
sometimes it is applied twice, once in the field and once by the data analyst. When
tower installers use a magnetic compass, the risk of error can be reduced by instructing
them to orient the sensors with respect to magnetic north and by correcting the readings
to true north when the data are analyzed. Fortunately, these days, most GPS receivers
can indicate true north, thus eliminating the need to consider magnetic north at all.