This paper introduces a new design procedure to obtain optimum solutions for multiturn-compensated loops. The magnetic-field mitigation problem is formulated by taking into account the thermal effects derived from the losses induced in the loops, in order to analyze the impact of this technique on the ampacity of the line. The IEC 60287 standard is used in the formulation of the multiturn-compensated loops, developing new expressions for the external thermal resistance and the proximity effect factor in the case of four equally loaded touching cables. Also, a 2-D finite-element approach is employed to verify those expressions and to validate the coupled magnetothermal problem. The performance of this technique is analyzed in terms of efficiency and operational costs.