Incidental work is a comparatively  minor task  that is complementary   to a principal job.  In determining whether a task is incidental and thus properly assign able to the tradesmen performing the principle job, the following points must be considered  (past practice or normal scope of the trade has no significance in incidental work ):

• Time involved in  relation to the principle job. ( A minor task or series of minor tasks performed sporadically over the duration of the principle job are incidental even though the cumulative time may be fairly large ).
  
• Whether the task is within the capabilities of  the principle  tradesman.
  
• Whether the task can safely be performed by the principle tradesmen. Incidental tasks are not limited to  those arising in the course of the principle job, but may occur also at the beginning or end of the job.

In the event of breakdowns and other unforeseen incidents that interrupt the flow of production as well as fires, accidents and the like, assignments may be made without regard to trade lines although trade lines are not to be disregarded where the time within which the repairs are to be made and the availability  of the appropriate tradesmen permit their  observance.