In some European countries, e.g. Germany, Spain or Czech Republic, smaller lattice towers are used for medium voltage (above 10 kV) transmission lines too.

The towers are usually steel lattices or trusses (wooden structures are used in Australia, Canada, Germany, and Scandinavia in some cases) and the insulators are either glass or porcelain discs or composite insulators using silicone rubber or EPDM rubber material assembled in strings or long rods whose lengths are dependent on the line voltage and environmental conditions.

Transmission towers must withstand various external forces, including wind, ice, and seismic activity, while supporting the weight of heavy conductors.

Ton shaped towers are the most common design, they have 3 horizontal levels with one cable very close to the pylon on each side.

[10][11] The design features electricity cables strung below a cross-arm atop a single pole which reduces the visual impact on the environment compared to lattice pylons.

These 36 T-pylons were the first major UK redesign since 1927, designed by Danish company Bystrup, winner of a 2011 competition from more than 250 entries held by the Royal Institute of British Architects and Her Majesty's Government.

[15] Poles made of tubular steel generally are assembled at the factory and placed on the right-of-way afterward.

In Argentina and some other South American countries, many overhead power lines, except the ultra-high voltage grid, were placed on tubular concrete pylons.

One example is a 61.3 m (201 ft) tall pylon of a 380 kV powerline near Reuter West Power Plant in Berlin.

Sometimes (in particular on steel lattice towers for the highest voltage levels) transmitting plants are installed, and antennas mounted on the top above or below the overhead ground wire.

On the Elbe Crossing 1 tower, there is a radar facility belonging to the Hamburg water and navigation office.

For crossing wide rivers and straits with flat coastlines, very tall towers must be built due to the necessity of a large height clearance for navigation.

In Spain, the overhead line crossing pylons in the Spanish bay of Cádiz have a particularly interesting construction.

The main crossing towers are 158 m (518 ft) tall with one crossarm atop a frustum framework construction.

In Germany, the overhead line of the EnBW AG crossing of the Eyachtal has the longest span in the country at 1,444 m (4,738 ft).

In order to drop overhead lines into steep, deep valleys, inclined towers are occasionally used.

These are utilized at the Hoover Dam, located in the United States, to descend the cliff walls of the Black Canyon of the Colorado.

Highly sloping masts are used on two 380 kV pylons in Switzerland, the top 32 meters of one of them being bent by 18 degrees to the vertical.

The most common forms are small rooftop poles used in some countries like Germany for the realization of overhead 400/230 volt grids for the power supply of homes [1].

One can find such a device at a steel work in Dnipro, Ukraine at 48°28'57"N 34°58'43"E and at a steel work in Freital, Germany at 50°59'53"N 13°38'26"E. In the United States such device may be more common as in other countries [2], [3] There are also real rooftop high voltage towers on industry buildings as at a steel plant in Piombino, Italy [4] and on a roof on an industrial building at Cherepovets, Russia at 59°8'52"N 37°51'55"E. Until 2015, on a residential highrise building in Dazhou, China at 31°11'28"N 107°30'43"E a powerline tower stood.

A structure of this type is Tower 9108 of a 110 kV high-voltage traction power line in Fulda [5], File:Mast9108-Fundament.jpg.

There are a variety of ways they can then be assembled and erected: The International Civil Aviation Organization issues recommendations on markers for towers and the conductors suspended between them.

Insulators electrically isolate the live side of the transmission cables from the tower structure and earth.

By using disks the shortest surface electrical path between the ends is maximised which reduces the chance of a leakage in moist conditions.

They consist of a short length of cable clamped in place parallel to the line itself and weighted at each end.

Towers will have a level of physical security to prevent members of the public or climbing animals from ascending them.

Some countries require that lattice steel towers be equipped with a barbed wire barrier approximately 3 m (9.8 ft) above ground in order to deter unauthorized climbing.

Such barriers can often be found on towers close to roads or other areas with easy public access, even where there is not a legal requirement.

The northern tower of Elbekreuzung 1 carries in a height of 30 metres a radar station for monitoring ship traffic on Elbe river on its structure.

The Tower 93 of Facility 4101, a strainer at Hürth south of Cologne, Germany carried from 1977 to 2010 a public observation deck, which was accessible by a staircase.