Pre-Installation Considerations: RTMS Echo Sensor

Providing a Proper Ground

Providing a low resistance earth ground connection is essential to achieving effective surge protection. Total resistance from the protected circuit to the earth should be less than 5 ohms. A grounding rod (see Figure A below) should be at least 6 ft (1.83 m) in length and placed as close as possible to the base of the RTMS Echo mounting pole. The grounding conductor should be flexible copper braid or copper wire 12AWG or larger.

Figure A

The earth grounding rod, together with proper ground of the breakout box, and surge protecting devices installed in close proximity of the mounting pole, create a barrier or a "sink hole" for any charges and surge coming towards the sensor from the surrounding area (see Figure B). These charges and surges may be caused by industrial noise, power surges, or lightning.

Figure B

Thunderstorm lightning is in its own class of destructive forces to sensors. Typically, it can generate 30 to 300 kA of current, far beyond the capabilities of any surge protecting devices. Therefore, a direct or near direct lightning hit may cause equipment damage even in the presence of surge/transient protecting devices. Because lightning is a major influnce on power line surge, it is important to understand the exposure to thunderstorms in the area where the RTMS Echo sensor is being installed. In areas that are exposed to large number of thunderstroms, protecting sensors will be more challenging.

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