Abstract: A liquid-proofing system for an electric motor, having a casing divided by two partition walls into three coaxially arranged chambers--a top chamber, an intermediate chamber, and a bottom chamber. The partition walls have openings for establishing communication between chambers and for the passage of a shaft interconnecting the shafts of the electric motor and pump. The top chamber is filled with an intermediate liquid, and the lower and the intermediate chambers are filled with the same oil as the oil filling the electric motor. Seals are provided which are formed by rotary and stationary parts and secured to the shaft and partition walls, respectively. The top chamber and the intermediate chamber communicate through pipes directly with the lower part of the bottom chamber, and the seals are installed in the intermediate chamber, the lower part of the bottom chamber and the pipe connecting it to the top chamber being filled with the intermediate liquid.