Type MI mineral insulated cable is truly a self-contained wiring system of insulated conductors and a rugged overall seamless protective copper sheath. This cable is able to withstand severe twisting, bending, and deforming pressures because the conductors do not shift or migrate within the dense highly compressed magnesium oxide within the copper sheath. This cable will operate over a temperature range of -40 to 85 C with standard Type O terminations and up to 250 C with special terminations. In addition to general wiring uses for service up to 600 volts maximum it has many uses as a communications cable by virtue of its excellent dielectric properties. Author
Annual Wire and Cable Symposium (2nd), Asbury Park, N. J., December 14-15-16, 1953.