Three pieces unions enable an independent rotation and the connection between pipes of an electrical equipment and enclosures or different devices of an explosion-proof equipment. Reducers and adaptors are used to connect equipment, enclosures, pipes and hubs of different diameters and threads, while closing plugs are used to close pipes ends and they are constructed with hex socket head to ensure the opening with special tools only. Open elbows, sealing fittings, nipples, couplings, rigid and flexible tubes compleate the electrical fittings series allowing the realization of a complete piping electrical systems.