The secondary of the Pole mounted Distribution is usually connected between the two phases of a MV line. The secondary voltage is a single phase voltage which is fed to the house. These transformers can be easily installed and do not require extensive mounting Structures.
Pole mounted Transformers come in sizes up to 500 kVA.These transformers have a fuse to protect against faults inside the transformer. They are also equipped with an interrupting device. These Transformers are tested to withstand the impulse of lightning. In the US, The secondary of these transformers has a centre tapping and therefore has three terminals.
The voltage between the end terminal and the centre tapping will provide 120V while the voltage between two end terminals will be 220 volts. These Single Phase Pole Mounted transformers can also be used to provide three phase LV supply.
Three pole mounted transformers are connected in wye or delta to get the desired connection. Besides, small size three phase transformers which can be mounted on poles are also available. Video Showing the Manufacture of Single Phase Transformers