Our Voltimum Experts answer your questions on a daily basis in our Technical Expertise area. This Question of the Day, about whether PVC cable should be contained in conduit if passed through polyurethane insulation, is answered by BASEC:
If PVC cable passes through expanded polysytrene insulation, it requires to be in conduit to prevent migration of the plasticiser from the cable to the polystyrene. Is the same true if it is in contact with polyurethane of polyiso (rigid polyisocyanurate)?
Answer: Only polystyrene thermal insulation is of serious concern for PVC sheathed cables. In general it is not required to place PVC sheathed cables in separate conduit if passed through polyurethane or polyisocyanurate thermal insulation. The thermal insulation polymers are different and do not have residual chemicals present that are found in polystyrene thermal insulation.
Thermal insulation manufacturers have confirmed this position with BASEC.
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