The ARCJ kits with the HESS sensor require an external +8 to +30 VDC power source. This sensor does NOT have a minimum threshold speed as does a magnetic pickup sensor. However, when the sensor is first powered up, the output state is indeterminate when the sensor is not detecting metal. The sensor face can be mounted flush into metal panels. The case is stainless steel and is supplied with 10 feet (3 M) of cable. The stranded shield wire is not connected to the sensor circuit or the case.
