Large, modern wind turbines normally use conical tubular steel towers. The primary advantage of this tower over a lattice tower is that it makes it safer and far more comfortable for service personnel to access the wind turbine for repair and maintenance. The disadvantage is cost.
The primary danger in working with wind turbines is the height above ground during installation work and when doing maintenance work. New Danish wind turbines are required to have fall protection devices, i.e. the person climbing the turbine has to wear a parachutist-like set of straps.The straps are connected with a steel wire to an anchoring system that follows the person while climbing or descending the turbine. The wire system has to include a shock absorber, so that persons are reasonably safe in case of a fall.
A Danish tradition (which has later been taken up by other manufacturers), is to place the access ladders at a certain distance from the wall, as shown in the image. This enables service personnel to climb the tower while being able to rest the shoulders against the inside wall of the tower.
Protection from the machinery, fire protection and electrical insulation protection is governed by a number of national and international standards. During servicing it is essential that the machinery can be stopped completely. In addition to a mechanical brake, the rotor can be locked in place with a pin, to prevent any movement of the mechanical parts whatsoever.