Introduction. According to the statistical data, electrical fires account for the majority of all fire accidents. Hence, better fireproofing of fuel and energy facilities is a relevant issue. The article addresses electrical fire extinguishment using high-expansion foam. An extinguishment time analysis methodology, applicable to fire extinguishment using high-expansion foam, has been developed to validate these solutions. The purpose of this article is to calculate the dependence between the fire extinguishment time and the foam consumption rate. The research objectives are to 1) identify the principal values to be used in the calculations and the list of input data; 2) to identify the dependence between the extinguishment time and the foam consumption rate using packaged transformer substation 2BKTP (1,000 kVA) as an example. Calculation methodology. The calculation methodology is based on the material balance equation between the amount of foam, applied for firefighting purposes, and the amount of foam, destroyed as a result of its contact with the heated wire surface, which is the main fire load inside burning electrical facilities. Research results. The co-authors have calculated the fire suppression time using packaged transformer substation 2BKTP (1,000 kVA) as an example. Dependencies between fire extinguishment time, specific foam consumption rate, and foam application rate are identified. Conclusions. The co-authors have identified the main values, needed to simulate a fire extinguishing model. They have also shown optimal foam consumption and application rates and offered their assessment of the applicability of high-expansion foam to electrical fires.