Hardware Installation
SCX 920 Installation Guide 5
sion acts as an insulator, raising the potential of the pipe with respect to
the ground.
When lightning strikes in the area of the installation, it drastically
changes the potential of the earth. Since properly grounded Andover
Controls units respond to changes in potential more rapidly than poorly
grounded electrical systems, a poorly grounded building tries to reach
ground through the Andover Controls system. The surge of current can
destroy electronic components on the controller board.
Surges of much lower potential than lightning also impact the reliability
of Andover Controls equipment.
Inspecting the Ground
You can check your ground as follows:
1. Check your ground by first inspecting the building power
distribution panel for earth ground termination. If the ground
termination is any of the following, it is not adequate and must be
corrected:
• Does not exist.
• Is connected to a corroded or galvanized pipe.
• Is connected using a small gauge wire (less than 14 AWG).
2. Be sure your Andover Controls cabinet is connected to the ground
with a copper conductor that terminates at the distribution panel.
Environmental Requirements
The SCX 920 operates in rooms with temperatures ranging from 32 to
120°F and with humidity up to 85%, non-condensing.
The controller must be in an Underwriter Laboratories approved
enclosure.
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