(36) Essential Services: The erection, construction, alteration or maintenance by public utilities or Municipal departments of underground, surface, or overhead gas, electrical, telephone, telegraph, steam, fuel or water transmission or distribution systems, collection, communication, supply or disposal systems, including towers, poles, wires, mains, crains, sewers, pipes, conduits, cables, fire alarm and police call boxes, traffic signals, hydrants, and similar accessories in connection therewith, but not including buildings which are necessary for the furnishing of adequate service by such utilities or municipal departments for the general health, safety or welfare.