Central Skills

Tasks which require the unique  and central skills of one particular trade are assigned to that trade (unless such task are incidental  to a principal job being performed  by other tradesmen  as discussed below). 

Overlapping Capabilities

To determine whether a particular skilled assignment falls within the scope of two or more trades and thus properly assign able  of any one of these trades  several  criteria must be considered, no one of which by itself is controlling .

• Level of skill involved.
• Type of  apprenticeship training.  
• Tools required. 
• Nature of the material being worked on. 
• Generally accepted notions of the trade. 
• Other criteria ( e.g.,  composition and size of the skilled work force.)  
• Past practices in a plant relating to skilled tasks (invariable, certain and unchallenged over such a long period that an agreement is assumed).     

The first six of these criteria will be considered in making the determination of whether a skilled task falls within the scope of two or more trades or only one.  Past practice is a limiting factor and is binding in ordinary situations if by clear and convincing proof it can be shown to exist as a fact by the party relying on  it.