Aprilaire 5000 Control Electrode 4311 made by Aprilaire. The frame measures 26¼ x 16 x 5/16". The diamond grid measures 1¼ x 5/8. This control electrode is used in all model 5000, from the first model to present.
The control electrode restrains the high voltage field created by the ionizing wires. The control electrode is a grid of expanded aluminum. This grid does not function as a prefilter. It prevents the ionizing field from confering a static charge to nearby duct work or equipement such as a ultra-violet air purifier.