If you thought that NFPA only addressed electrical safety and wiring, you likely haven’t examined an NFPA document since before 1997. NFPA 79 addresses many vital aspects of machine guarding. The 1997 version was virtually identical to EN 60204-1 regarding operator controls.
Beginning in 2002, NFPA 79 addressed Control Reliability and the need to do a risk assessment. Safety PLC’s and Safety Controllers were approved for general industry in this standard beginning in 2002 and approvals were provided in the 2007 standard for integrated machine-drive safety systems. The 2012 version has incorporated additional changes that bring this standard into harmonization with IEC 60204-1. The changes are not drastic, but provide additional guidance and definitions of requirements.
NFPA 79 is THE standard for E-Stop control. E-Stops just aren’t plain ol’ E-Stops anymore. According to NFPA 79, “the function of the E-Stop must be ensured.” That is a very big and important phrase. When looked at properly, most control systems designers will determine that the E-Stop circuit must be Control Reliable.
If you have further questions regarding NFPA 79 and/or E-Stop circuits and function, contact us today for help.