The book contains basic concepts on the purpose and arrangement of protective earthing and other protective measures of electrical safety in electrical installations with a voltage of up to 35 kV. The third edition describes a promising protective measure - protective disconnection. The draft of the new Electrical Installation Code has been taken into account. At the end of the book, the most frequent questions from readers are answered. The book is intended for electricians serving electrical installations, as well as employees of other specialties related to work with the use of electricity.