In this paper, the thermal degradation of electro-conductive fabrics exposed to high current impulses is studied by using an equivalent resistive circuit and a technique commonly applied to the analysis of exploding wires. A method to estimate the threshold burst current of conductive fabrics is derived based on the so-called specific action, which is defined as the integral of the squared current density over the time applied at critical locations of the fabric such as the contact areas between yarns. The model has been experimentally validated on woven and non-woven fabrics using lightning impulse currents applied to the conductive fabrics coated with Cu-Ni alloy. A general rule for determining the dimensions of conductive fabrics as a function of the input-current specific-energy levels has also been derived.