I have ordered a .G.C. CU. COND. 3 CORE XLPE/SWA/PVC 50mm² 11K.V. ( no.of diameter of wire before stranding 7/3.02) but unfortunately I received (no. of diameter of wire after stranding 7/2.754) after negotiating with the supplier they said this is the size of wires after stranding. is this correct???
A 3.02 mm diameter wire has a cross-sectional area of 7.16 mm2. 7 strands will have a total CSA = 50.1 mm2.
A 2.754 mm diameter wire has a cross-sectional area of 5.957 mm2. 7 strands will have a total CSA = 41.7 mm2.
It seems to me that you are correct and they are not.