Continuum Power Supply Reference 7
Building Ground Requirements
Be sure that all equipment from Andover Controls is grounded to true Earth ground.
True Earth ground protects the equipment from transients and other power surges in
the area. We cannot guarantee that the controller system will operate as documented
without a properly grounded installation.
An example of a sub-standard ground is a galvanized steel cold water pipe. As the
pipe corrodes, it does not act as a true ground. The corrosion 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 the equipment.
Inspecting the Ground
Be sure to have your grounds inspected before you begin the installation process to
be sure your municipality follows the National Electrical Code. Many municipalities
do not follow the code and often have substandard electrical grounds.
Check your ground as follows:
Inspect 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).
Be sure your Andover Controls cabinet is connected to the ground with a copper
conductor that terminates at the distribution panel.
Lightning Protection
Metal oxide varistors are built into the power supply to protect against power line
transients.
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