Step 1 - Marking out and location
Make sure you choose a good location. Wind turbines are useless
in bad locations. Out of 100 people who phone us up and say "it's very windy where I live" perhaps one of them has a site worth surveying. See this page for some guidelines
We had an oddly shaped plot which limited space
Once you are happy with your chosen location, location, location! start marking out the position of the Spirafix ground anchors. I cut a piece of string, made a loop in one end and trimmed it so it was the radius of the circle for the four, peripheral anchors. Because space was a little limited and the ground quite uneven the piece of string was also ideal for finding the best location for the central anchor. I did this by attaching one end to a stake that represented the central anchor (A1) and walked the circle whilst holding the end.
At this stage it's very important to decide which direction you will raise and lower the tower. You can't change this afterwards without moving all the perimeter ground anchors! On this particular site it was very difficult to drive the central anchor in horizontally because the ground was very hard and there were quite a lot of stones beneath the surface. The slight angle we ended up with dictated the raising and lowering direction
I really can't stress enough how important accuracy is at this stage. The anchors must be spaced correctly or you will have major problems with the length of the guy ropes. If the radius arrow on figure 1 represents the tilt direction then anchor A4, A1 and A3 MUST be in line and equidistant (we used the pipes and a sleeve to check that the anchors are in line) This is especially so for the left and right anchors as the guy ropes could over tighten before the mast is vertical (figure 2) or be slack when the mast is vertical. Figure 2 exaggerates the effect on the length of your pre-adjusted guy ropes when the side anchors are in front of the central anchor.
Step 2 - Driving in the anchors
Drive in the central anchor first using a decent size lump hammer. You can turn the anchor screw with a large spanner if you hit a stone or very hard earth. We were all very surprised how easy it was to drive them in even though the ground was very stony and hard. (5 mins per anchor) Don't whack them in with the bolt in the anchor or you'll ruin it.
Start with the central anchor and when it is nearly all the way in stop and use a large spanner to turn it a little so the nut on the end of the anchor is proud of the ground. You'll need to put the spanner back on it to tighten the anchor bracket. This is a good time to trial fit the centre bracket and bolt and check the raising/lowering direction.