A collecting electrode panel assembly for use in an electrostatic precipitator (10) comprises a plurality of collecting electrode plates (22) disposed in successively aligned relationship beneath and suspended from an electrode support beam (14) supported upon support beam (60) suspended from the upper region of the housing (12) of the electrostatic precipitator. The support beam (60), comprises an elongated flange support beam having a generally J-shaped cross-section having an upright leg (62), a base flange (64) extending transversely outward from the lower end of the upright leg, and a lip flange (68) extending upwardly from the outward edge of the base flange (64). The base flange (64) provides a support surface (66) upon which the end of the electrode support beam (14) rests. Notches (80) are cut in the lip flange (68) of the support beam (14) at appropriate locations to receive at each location the end of an electrode support beam (14). Hanger rods (70) are mounted to the upright leg ( 62) of the flange support beam (60) for suspending the support beam (60) from the housing of the electrostatic precipitator. The hanger rods (70) are adjustable so as to permit the elevation of the support beam (60) to be adjusted so as to assist in leveling the collecting electrode support beams (14) supported from the flanged support beam (60).