... . Can be replaced for the module. Product DescriptionNS1-(D, C, B) 5 series surge protection device (in short: SPD, alias ... , surge arrester) is suitable for TN-S, TN-C-S, TT, IT etc. power supply system of AC ... Scope and Installation PositionNS1-(D, C, B)5 surge protective device is applicable for D,C,B grade lightening-proof, installed ... , 8 pieces.Model and Meaning NS1-(D, C, B)5 Lightning Arrester