The magnetisation loss in Bi-2223 superconducting tapes can be significantly decreased only when the filaments are electrically decoupled. An expression is presented for the amplitude of the coupling currents in the outer filaments. In an Ag-matrix tape parallel to the field, the filaments can be decoupled just by twisting them. In an Ag-matrix tape parallel to the field, the filaments can be decoupled just by twisting them. In perpendicular field a higher matrix resistivity must be realised e.g. by introducing ceramic barriers between the filaments. The increase in matrix resistivity caused by such barrier is quantified by measuring the frequency-dependence of the AC loss.
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