An interplanetary shock caused a rapid compression of the magnetosphere on August 27, 1978. The ISEE 1/ISEE 2 pair of satellites were in the frontside magnetosphere before the shock, and subsequently a magnetosonic wave front, the magnetopause, and the bow shock passed the ISEE satellites in a very short time. Previous papers determined boundary velocities from magnetic time delay measurements. These papers form a starting point for the study of electric field data during these events. By a combinmation of electric and magnetic field data it is possible to determine both the magnetosonic velocity and the magnetopause velocity, in good agreement with the magnetic time delay measurements. Furthermore, it is possible to establish with good confidence that during this compressional motion the E¿B velocity was toward the magnetopause from both sides, ~75 km s-1 from the earth side and ~50 km s-1 from the sun side. A power conversion flux close to +400 W km-2 could be determinedfor the magnetopause. A sunward potential drop of 135--280 V was detected near the bow shock, and in this case the power conversion flux was negative, and in the range -(80--160) W km-2), or ~10% of the solar wind kinetic energy flux.