Can anyone tell me the difference between an auxiliary gutter and a metal wireway. The only difference I see is that an auxiliary gutter cannot be longer than 30 feet and it allowed to have busbar in it. Is it the busbar that really distinguishes the two? Otherwise, why wouldn't we just call everything a wireway instead of a gutter?

Thanks

If you look at art. 366.2, and art. 376.2 you will see the difference. Auxiliary gutters are for augmenting wire space at " meter centers, distribution centers, and simular points of wiring systems." Thats why it is limited to 30 feet. Metal wireways can be used for all other applications and has no length restrictions. Hope this helps and have a happy and safe holiday. Mountainman

This is still not very clear to me. Let's say for example that I have a gutter/wireway above a couple of panels with chases. It does not extend 30' past the panels. Does it matter whether I call it an auxiliary gutter or a wireway, because it seems like either one would apply in this case?

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.