Important Safety Instructions
Compliance with ATEX and HAZLOC safety standards is required when installing wireless Watchman Air sensors in a hazardous rated location. These standards specify that the sensor body must have an electrical resistance to earth ground of less than 1 GigaOhm. This requirement helps to ensure that a static charge does not accumulate on the sensor body, which could then serve as an ignition source. The below attached procedure demonstrates how to verify that an installed sensor meets this requirement.
The following components are required to verify compliance with safety standards:
- A megohmmeter with a test voltage of 500 volts and the required test leads.
Note: The procedure uses AEMC® Megohmmeter model 6528. You can use a different brand and model of instrument as long as it meets the criteria for 500-volt test voltage and has a minimum operating range of 1 GigaOhm.
- 1 Gigaohm verification resistor
Note: This procedure uses a 1G Ohm, 5 Watt, 1% Tolerance, Axial Lead, High voltage glass glazed wire-wound resistor.
Additional Installation Notes:
The ‘machine ground reference point’ may be quite far away from where the sensor is installed. Meaning, the test leads on the instrument may not reach between that reference point and the body of the sensor. In this case it is acceptable to use a pin-point probe tip and firmly press it to a bare metal surface of the machine. An example could be area where the machine's paint was removed under the area of the sensor, exposing bare metal and using a section of that area that does not have adhesive on it could be acceptable.
Download the procedure below: