Yes, it is necessary to use the full neutral cable (the same size as L1,L2 and L3):
1) For iEM3300, L1,L2,L3,Neutral are 50 mm2 / 1AWG;
2) For iEM3100, L1,L2,L3,Neutral are 16 mm2 / 6AWG;

Released for:Schneider Electric Thailand