I concure with 5kW 4 anchor points are required to allow the tower to be held from both sides (each 90 degree from pulling point) with one behind to stop it being pulled over centre.
If possible place the anchor points such that two share the load from your prevailing winds ie if Westerly winds were your strongest place anchors at N/W and S/W to share the load. Also if you have a sloping site try to arange the pull up point at the lowest position, this facilitates the raising of the tower, as technically the tower starts from above the horozontal if lowered uphill.
Minimum distance from base to each anchor point is 1/2 height, but most preferably tower height. The reason for this is that the greater the distance the less the stress on anchor wires & anchor points.
Last anchor wire should be as close under the tower top that you can get without the possibility of fowling the blades. The top wire carries the force of the turbine wanting to move away from the wind, those below stop the tower from bending.
Bergy have an istallation manual on there site for one of their unit which is worth a read.
regards Allan
