Transformers are devices that take the electricity of one voltage and change it to another voltage. Transformers convert the distribution line voltage (12 kilovolt) to the voltage used by homes and businesses (120 volts to 480 volts).
In Alameda’s electric system, there are two categories of transformers. Transformers that look like cylinders are mounted on utility poles. Other transformers are contained in green boxes, which are mounted on the ground. Undergrounding district transformers fall into the second category.