This code deals with aspects of the application and installation requirements of shunt diode barriers. It gives guidance on techniques which have been found to be satisfactory and illustrates the main points by reference to some possible solutions, but it does not cover all possible acceptable installations of shunt diode safety barriers. Earth connections are discussed because of their fundamental importance. The use of resistors and switches in the hazardous area is also considered in some detail, since they can frequently be used without further certification.