An electrical cartridge heater is used to heat water to a temperature of 50C in a manufacturing process. The heater is powered by 240V source and draws 15A of current.

The length and diameter of the cartridge heater are 60cm and 1.5cm respectively. If the heater is immersed in the water such that the heat transfer coefficient is 4500 W/m² K, find the surface temperature of the cartridge heater.