One of the most important . measures to achieve good EMC characteristics is to bond all metallic (conducting) structures together with many wide connections. Connect metal to metal by as large area as possible, with good surface conductivity. These joined parts form a conductive equipotential structure, that act as a reference plane or ground for all electrical and electronic circuit in its vicinity. In practice, the apparatus body and the metal casing, forms this reference plane. In most cases, the ground planes in PCBs must also be connected to the reference plane to achieve the desired EMC properties.