Are plumbers who work at construction sites considered plumbers?

Plumbers who work on construction sites are not plumbers.

The so-called "plumbers" at construction sites usually refer to workers in professional construction of plumbers, not plumbers. Plumbing and electricity construction workers are management personnel at construction sites and are not directly engaged in production operations and are not workers. Moreover, plumbers and electricians are generally not referred to as "plumbers" in construction sites. They are all directly called plumbers or construction workers. Therefore, plumbers who work on construction sites are not plumbers, so do not confuse the two.