Does wireway need to be UL (or otherwise) listed? The NEC only mentions the need for a manufacturer's label to be visible.

The company I work for has wireway routinely made by a local metal working shop. These wireways have been used on numerous jobs and in various cities and municipalities. Apparently no inspectors or engineers have ever had an issue with this unlisted and unlabeled wiring system. The "homemade" wireways are custom shaped for each installation so it is BLATENLY obvious that they are not something that got spit out of a factory by the thousands. There is no way that countless "authorities having jurisdiction" could have missed this. The units are very well constructed but don't they need to be UL listed?

So what are the rules governing wireways?

See Articles 376 and 366 part III.
Most AHJ's will accept a well made wire way that is made of good quality materials.
Most sheet metal shops know the mechanical construction requirements for these wireways and or gutters.

Wireway and other such items do not always have to be listed.The NEC requires that they be approved and listing is one of the ways that an ahj may determine suitability for the job.See 110.2 and 110.3.It is up to the ahj to give approval or denial of use.Some will argue but before you do look up the definition of approved in your code book.

Over the years, I have read a number of UL standards. What is interesting is that every single one, where a particular construction or material is considered "normal" or "typical" will have a provision allowing for the evaluation of alternative materials.
Often the standards will define what strength, etc., is required. So, as an example, one might evaluate conduit made of something besides steel, or pressure tanks in some shape other than ASME profiles.
Which brings us to other standards... for example, do you know the 'real' difference between RMC ans Sched 40 galvanised water pipe? (See the ASTM standards to find out).

IF I were to0 manufacture something to meet a need that was not properly addressed by something readily available, I would make it a point to find out what criteria the "usual" stuff met, and honestly ask myself "would my widget pass these tests?"

John, I get your point and agree with your concept. In some cases though, the code requires us to inspect for a Listing. Such is the case with RMC. I don't have access to the ASTM standards but seem to remember that RMC is not tested for internal pressure. Similarly, plumbers PVC is not tested for crush resistivity. Since these products are only tested and Listed for their respective application they are not appropriate for other use.
George

George, I understand your perspective. Yet, the NEC is clear that the final authority is the AHJ. Don't misuncerstand, I am NOT advocating anyone taking a cavalier attitude toward listing marks!

Actually, there is only one difference in the ASTM specs between plumbing pipe and electrical conduit....conduit has a "smoothness" spec, while plumbing pipe is silent on the issue. (A good trivia q).

NEC requires that stuff be suitable for its' environment. That can be a problem when there is no manufacturer of a suitable product. I was once involved with sump pumps and such, that were to operate in highly corrosive places. Galvanised steel was out of the question....and there was no manufacturer of stainless steel conduit. Care to guess how the problem was solved? And, I hasten to add, by a manufacturer who had several products UL listed, and a listed panel shop.