We have conducted experiments with aluminum, copper, and gold wires arrays to study x‐ray production, z‐pmch stability, and heating mechanisms. Time‐resolved x‐ray pinhole camera data and PCD data clearly show that the maximum in the keV x‐ray production occurs after peak compression during an expansion phase.The data are consistent with a sheath whose width is determined by the number of wires of the initial array (azimuthal uniformity) and the array diameter. The final stagnated size of the pinch is set by that sheath thickness. The stagnation event is characterized by a relatively uniform initial pinch reaching, in some cases, a diameter< 1 mm, followed by a disruption and increased x‐ray production. The source of this energy is apparently not kinetic. The kinetic portion of the energy should have been converted to thermal energy near the time of maximum compression. For aluminum and copper wire arrays, heating from classical Spitzer resistivity is insufficient to explain the observed x‐ray yields. While our present data does not show the actual location of current sheath nor does it give the position of non‐radiating plasmas and, hence, is incomplete, the data when taken as a whole is strongly suggestive of enhanced resistive dissipation and an MHD instability with a helical shape.