The electrical properties of the control glass fibre/epoxy panel and of the glass fibre/epoxy/0.1 wt.% CNTs composite, prepared with or without the application of an electric field, were studied by DC and AC conductivity measurements. The DC conductivity of all materials in both the through thickness (electric field direction) and the in-plane directions are illustrated in Fig. 6(a). A sharp increase of the conductivity, of more than six orders of magnitude, is observed in the samples containing MWCNTs (over 10−4 S/m) compared to the reference glass fibre/epoxy (below 10−10 S/m). This is attributed to the formation of a percolating conductive nanotube network in the material. Furthermore, the in-plane conductivity is more than one order of magnitude higher than that in the through thickness direction in all CNT containing composites. The anisotropy observed is due to the geometry of the insulating glass fibres which results in conductive epoxy/CNT regions that are continuous in the in-plane direction at the layers of the fabric that are aligned to the measurement field. These regions which correspond to half of the thickness of the 0/90° layup are connected in parallel with the insulated domains of the material and dominate the conductivity response. In contrast, in the through thickness direction the conductive epoxy/CNT regions are interrupted by the glass fibres, resulting in a serial configuration which is influenced more strongly by the low conductivity phase. The application of the AC field during infusion and curing results in an increase of the through thickness conductivity by about one order of magnitude. The through thickness conductivity for the CNT containing material without the application of the field is approximately 1.7 × 10−4 S/m. This value increases to 8.4 × 10−4 S/m with the application of a current density of 15 A/m2 and to 1.4 × 10−3 S/m at the highest current density of 45 A/m2. This is in agreement with the results of on-line monitoring and microscopy and can be attributed to the occurrence of preferential aggregation and nanotube alignment in the field direction. The in-plane conductivity remains almost unaffected by the application of the field, with a value of about 5.2 × 10−3 S/m without the field and a value of approximately 7.2 × 10−3 S/m with the field application.