Question: Can you make mesh pockets for arc rated clothing on the outside? Will this mesh lower the arc rating.
Answer: No a mesh pocket which has material over or under will not negatively affect the arc rating IF the mesh is either an arc rated material or tested for arc flash. Most use aramids or aramid Lenzing blends for the mesh. You do not want polyester or nylon (even if they claim to be FR) only arc rated or arc tested, non-melting materials should be used in a pocket.
Nomex and Kevlar are quite common. SSM and Gehring both have lots of these meshes so that should be easy (Please add other manufacturers and when we have confirmed they have proper ones, we will add them).
Lenzing Fiber is great in a blend. Most use Tencel (officially non-FR in small amounts in blends since it absorbs moisture like cotton) with Protex modacrylic and other fibers to make an FR blend.
Nomex or Kermel Lenzing are really common along with Twaron and Conex and Yantai (a Chinese meta-aramid)/Lenzing or Conex Lenzing serve the same market.
Lenzing FR is FR rayon which is extruded with FR inherently in the fibers but feels like cotton.