Lightning Protection; Building Ground Requirements - Andover Controls SCX 920 Installation Manual

Cables that form Infinet are 24-gauge, single-twisted-pair, tinned,
shielded copper wire.Use the following cables 1 or their equivalents:
• Brand Rex # H 9002 (single-pair)
• Anixter # 9J2401021 (single-pair plenum cable)
The cable should have a nominal impedance of 100 Ohms and a nominal
velocity of propagation of 78%. Capacitance of Infinet cable should be
nominal, below 12.5 pF/ft between conductors and below 22 pF/ft be-
tween the conductor connected to ground and the next conductor.

Lightning Protection

Lightning Arresters are required at each point where a bus cable enters
or exits a building. Use the following arrester:
Two pair gas tube arrester, Andover Controls # 01-2100-299

Building Ground Requirements

Warning
Be sure that all Infinity products from Andover Controls Corporation
are grounded to true earth ground. This kind of ground protects the
equipment from transients and other power surges in the area.
We cannot guarantee that the controller system will operate as
documented unless you properly ground all controllers.
Warning
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 and often have
substandard electrical grounds.
An example of a substandard ground is a galvanized steel cold water
pipe. As the pipe corrodes, it does not act as a true ground. The corro-
1. You can also use any cables you may already have in place for ACNET or LBUS.
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SCX 920 Installation Guide