These low noise transformers operate at reduced noise levels. The vibrations within the magnetic steel core have been greatly reduced, thus lowering the humming of the transformer to 3dB to 5dB less than NEMA/ANSI standards. Available in aluminum or copper windings, they feature a 220°C insulation system with a 150°C, 115°C, or 80°C rise. Although they are quieter, installation can influence their noise level and care should be taken in following acoustical principles as well as proper installation procedures. Closets and corners should be avoided as they act as megaphones by seemingly increasing noise levels.