ISO 13851:2002

This International Standard specifies the safety requirements of a two-hand control device and the dependency of the output signal from the input signals.
It describes the main characteristics of two-hand control devices for the achievement of safety and sets out combinations of functional characteristics for three types. It does not apply to devices intended to be used as enabling devices, as hold-to-run devices or as special control devices.
This International Standard does not specify with which machines two-hand control devices shall be used. It also does not specify which types of two-hand-control device shall be used. Moreover, it does not specify the distance between the two-hand control device and the danger zone.
This International Standard provides requirements and guidance on the design and selection (based on a risk assessment) of two-hand control devices including their assessment, the prevention of defeat and the avoidance of faults. It also provides requirements and guidance for two-hand control devices containing a programmable electronic system.
This International Standard applies to all two-hand control devices, independent of the energy used, including:
two-hand control devices which are or are not integral parts of a machine; two-hand control devices which consist of one or more than one separate element.