This document applies to the application design and installation of electrical equipment, control circuits and safety-related systems for furnaces which are operated with solid, liquid or gaseous fuels and their ancillary equipment. It specifies requirements to meet the operating conditions of furnaces, to reduce the hazards of combustion and to protect the heated systems from damage e.g. by overheating. Such furnaces and the electrical equipment can be part by way of example of the following plant: a) water heating systems; b) steam boiler installations (steam and hot-water boilers) and heat recovery steam boilers; NOTE 1 – The requirements of this document apply according to the electrical equipment of electrically heated steam boilers. NOTE 2 – Seagoing vessels and offshore facilities are governed by International Maritime Law and as such are not within the scope of this document. These requirements can be used for such facilities. c) warm air heaters; d) hot-gas heaters; e) heat exchanger systems; f) combustion chambers of stationary turbines; g) as long as no other standard is applicable for combined heat and power stations, we recommend the use of the requirements of this document; This document can also be used as reference for electrical equipment requirements for thermo-processing equipment. The requirements in this document are not applicable to electrical equipment for: a) non-electrically heated appliances and burner control systems for household and similar purposes; b) furnaces using technologies for the direct conversion of heat into electrical energy; c) combustion chambers of non-stationary prime movers and turbines; d) central oil supply systems for individual heating appliances; e) furnaces using solid fuels for heating purposes for household use with a nominal thermal output up to 1 MW; f) furnaces which are used to heat process fluids and gasses in chemical plant. This document can be used as a basis for the requirements place ...