ActronAir Indoor Evaporator EC Plug Fan and Impeller 355mm 3-Phase is a mid-range EC variable-speed plug fan for commercial ducted systems in the lower-to-mid commercial capacity range, where the 355mm impeller delivers the specific airflow volume suited to these indoor coil configurations without the higher power draw of the 400mm and 500mm variants. EC plug fans in this diameter range are commonly used in multi-fan commercial indoor unit configurations -- when one fan fails in a multi-fan array, system capacity drops immediately and replacement should be prioritised before compressor high-discharge temperature protection activates. Isolate power at mains before replacement -- EC motors and variable drives retain dangerous residual voltages for up to 5 minutes after power isolation.