Abstract: An electric heater adapted to be mounted against a flat wall surface has a box-like housing of sheet metal, the housing being partitioned to provide a heating section and a terminal box section. The housing has a generally flat rear wall with an aperture positioned to provide manual access to the terminal box section, the aperture having peripheral flanges defining a recess adapted to receive and locate a cover plate. The cover plate is secured to the rear wall and accommodated with the recess. The cover plate is formed with a groove for locating a power cable clamped to it by means of a clamping plate, and includes an indented portion formed with an opening aligned with the groove to receive the power cable which extends into the terminal box section.