Control Circuit (of a machine) : The circuit of a control apparatus or system that carries the electric signals directing the performance of the controller but does not carry the main power current
NFPA 79 Electrical Standard for Industrial Machinery, 2002 ed. http://www.nfpa.org/assets/files/AboutTheCodes/79/ 79-A2002-rop.pdf, (Electr Std for Ind Machinery - Amer) {225 NFC}