Informational equipment are difficult systems which performance reliability depends on a number of internal and external factors. One of the most important external factors is the quality of supplied electricity. Dependence of performance reliability of informational equipment upon the quality of supplied electricity, the impact of equipment themselves on the feeding system/net are discussed in this work. The standards of quality of electricity are overviewed, the deviations of voltage and their influence over informational equipment are evaluated. Means of increase of reliability, their structure and course of performance are described, their advantages and weaknesses are specified. Electrical ground system has major influence over reliable performance. In case of incorrect installation of the system it is possible to cause system foul-ups or even put a human life at risk. The influence of informational equipment over feeding net/system is evaluated in this work, the example of calculation of workload is presented.