Essential services. Nothing in this chapter shall preclude the construction, operation and maintenance of public utility, transmission, distribution or collection systems in any zone for water, gas, telephone, or electric service subject to the conditions of this chapter. Such systems may include systems of poles, wires, underground pipes, conduits, ducts and transformation equipment, including substations and appurtenances, necessary for the transmission and/or distribution of the commodity or service rendered by the public utility to its customers.