Jerry asks this question, which concerns whether PVC cable should be protected by conduit if passed through polyurethane insulation. It has been answered by BASEC (Theme – Cable, Wiring and Wiring Accessories):
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Question: Does PVC cable need to be passed inside conduit if going through polyurethane insulation?
If PVC cable passes through expanded polysytrene insulation, it requires to be inside 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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