Wieland fasis test plugs for wkf and wkc din rail terminal blocks wieland z129997530 this grey test plug with tension spring connection from wieland is for wkfwkc terminal blocks equipped with a 135a current rating 400v rated voltage and valid for both fine stranded and solidstranded wires with a cross section of 013 15mmsup2 wieland z129997530 test plug wkf and wkc ps wkcf ob