The invention relates to a liquid cooling element for cooling heat generating elements of frequency converters, in particular, and an arrangement for connecting the liquid cooling element. The liquid cooling element 2 is provided with two channel systems: horizontal channels 3, 4 and transverse channels 5 connecting said horizontal channels. The liquid cooling element 2 is characterized by consisting of one integral piece, the transverse channels 5 being arranged eccentrically to the horizontal channels 3, 4 such that the longitudinal axis of the transverse channel 5 is closer to the lateral face of the cooling element than the longitudinal axis of the horizontal channel 3, 4 and the outer edge of the transverse channel 5 extends closer to the lateral face of the cooling element than the outer edge of the horizontal channel 3, 4. The liquid cooling element is connected to protect the liquid cooling against leakage such that around the pipes supplying cooling liquid into the horizontal channels there is arranged a second pipe 22, 23 having a larger diameter.