A heating element for a wind turbine rotor blade including: two electrical connectors adapted to be connected to electrical supply lines of the wind turbine rotor blade, and a defined geometry configured to be arranged on a specified surface area of the wind turbine rotor blade. The heating element is provided with a position indicator adapted to be aligned with a leading edge of the wind turbine rotor blade.

A method of determining a temperature of a heating element (210) of a wind turbine blade (200) includes heating the heating element by providing a heating current in the heating element. The method includes measuring a first value (I.sub.1) of the heating current at a first time. The method includes determining a first temperature (T.sub.1) of the heating element using the measured first value of the heating current and a known functional dependency (410) between the heating current in the heating element and the temperature of the heating element.

A wind turbine blade comprising an anti-icing system (30) comprising an electrothermal heating arrangement (35) configured to provide heat to an external surface of the blade, wherein the electrothermal heating arrangement is connected to a power supply interface (38) of the wind turbine blade by way of a power supply conductor (40) and an earth conductor (44). The blade further comprises a lightning protection system (31) having a lightning strike protection device (56) associated with an electrothermal heating element of the heating arrangement, the lightning strike protection device being connected to a lightning down conductor (50) of the lightning protection system leading to a current transfer unit (54) configured to transfer lightning current to a rotor hub, in use. A transient current limiting device (60) is connected in a conductive path (62) between the lightning down conductor of the lightning protection system and the earth conductor of the anti-icing system, thereby permitting induced parasitic currents in the lightning down conductor to earth through the anti-icing system. This provides the benefit of preventing electromagnetic emissions that can, otherwise, cause interference with electronics in the vicinity of the wind turbine. Thus, allowing the wind turbine to comply with established EMC standards.

A wind turbine rotor blade including a blade root, a blade tip, a leading edge, a trailing edge, a suction side, a pressure side and a heatable surface area including at least one electrical heating element, wherein the heatable surface area covers a section of the leading edge and has a first edge facing the blade tip, a second edge facing the blade root, a third edge arranged on the suction side and a fourth edge arranged on the pressure side, characterized in that the wind turbine rotor blade includes a first layer of an electrically insulating material, wherein the first layer is smaller than the heatable surface area and is arranged on top of the at least one electrical heating element along the leading edge and such that it extends beyond the first edge.