Related Legal Terms & Definitions. 1  COMPETENT WITNESS One who is legally qualified to be heard to testify in a cause. 2  RESPECTABLE WITNESS One who is competent to testify in a court of justice. 3  CREDIBLE WITNESS A credible witness is one who is competent to give evidence, and is worthy ofâ¦.
In general, combustibility of polymers depends on their chemical structures. Polymers with more carbon atoms in their macromolecular structure (e.g., PE, PP, PS, PMMA) are more combustible than polymers containing halogen atoms (e.g., PVC, PVDC, PTFE).
Rigid polyvinyl chloride conduit (PVC) is a rigid nonmetallic conduit that provides many of the advantages of RMC, while allowing installation in areas that are wet or corrosive. PVC conduit is an inexpensive, easily installed raceway. Itâs lightweight, easily cut, and relatively strong.