The use of mPPE - wire results in cables with very small diameter in each voltage class. The tinned 7 - and 19 - stranded copper conductors are mPPE insulated. With a hardness of 91 Shore A they are tough and can be processed such as PVC. This is significantly thinner and lighter in the comparable operating voltage. mPPE insulated wires meet the strict vertical flame test (VW1) to UL 1581 mPPE = modified Polyphenylene Ether