An auxiliary gutter would be and addition to the wire space for equipment. Thats why the code allows busbars in them. Wireways are not restricted to just equipment or lengths. Auxiliary gutters can extend 30' from the equipment. Wireways you can install any amount of length and are not restricted to just service equipment and the like. Even though both are physically the same piece of product, the definition is the key. Wireways you can install anywere on the job, but auxiliary gutter would for all practicle porposes would be in your equipment rooms.
