A remote interlock connector [1040.10(f)(3)] is required on all Class IIIb and IV laser systems. The purpose of the remote interlock connector is to permit the user to connect a remote barrier interlock, emergency stop switch, or similar device. The circuit must be such that, when the terminals of the connector are open, human access to laser radiation is prevented. The electrical potential across the connector terminals must not be greater than 130 volts rms. A shorted mating connector may be provided by the manufacturer to allow the product to be operated when the remote interlock connector is not being used.