This International Standard specifies principles for the design and selection – independent of the nature
of the energy source – of interlocking devices associated with guards and provides guidance of measures
to minimize the possibility of defeat of interlocking devices in a reasonably foreseeable manner.
This International Standard covers the parts of guards which actuate interlocking devices and
principles for the design, selection and application of trapped key interlocking devices and systems for
machinery applications, independent of the type of energy used to control them or that they control
NOTE – ISO 14120 specifies general requirements for the design and construction of guards provided
primarily to protect persons from mechanical hazards. The processing of the signal from the interlocking device
to stop the machine and prevent unexpected start up is dealt with in ISO 13849-1 or IEC 62061:2015.