Grounding Installation Requirements - Emerson ROC809 Instruction Manual

ROC800-Series Instruction Manual

2.1.5 Grounding Installation Requirements

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Although the ROC800 can operate on different DC voltages based on
the installed Power Input module, it is good practice when using a
battery-backed system to install a low-voltage cutoff device to help
protect batteries and other devices the ROC800 does not power.
Similarly, when the ROC800 uses a PM-24 Power Input module with a
24 V dc battery-backed system, it is a good practice to install an
appropriate low voltage cutoff device to protect the battery back-up.
If your company has no specific grounding requirements, install the
ROC800 as a floating system (unconnected to ground). Otherwise,
follow your company's specific grounding practices. However, if you
are making a connection between a grounded device and the ROC800
EIA-232 (RS-232) port, ground the ROC800 Power Input module either
by connecting the PM-12's BAT– to ground or by connecting either of
the PM-24 or PM-30 module's negative Power Inputs to ground.
The National Electrical Code (NEC) governs the ground wiring
requirements. When the equipment uses a DC voltage source, the
grounding system must terminate at the service disconnect. All
equipment grounding conductors must provide an uninterrupted
electrical path to the service disconnect. This includes wire or conduit
carrying the power supply conductors.
 The National Electrical Code Article 250-83 (1993), paragraph c,
defines the material and installation requirements for grounding
electrodes.
 The National Electrical Code Article 250-91 (1993), paragraph a,
defines the material requirements for grounding electrode
conductors.
 The National Electrical Code Article 250-92 (1993), paragraph a,
provides installation requirements for grounding electrode
conductors.
 The National Electrical Code Article 250-95 (1993) defines the size
requirements for equipment grounding conductors.
Improper grounding or poor grounding practice can often cause
problems, such as the introduction of ground loops into your system.
Proper grounding of the ROC800 helps to reduce the effects of electrical
noise on the ROC800's operation and protects against lightning.
Install a surge protection device at the service disconnect on DC voltage
source systems to protect against lightning and power surges for the
installed equipment. All earth grounds must have an earth to ground rod
or grid impedance of 25 ohms or less as measured with a ground system
tester. You may also consider a telephone surge protector for the dial-up
modem communications module.
Installation and Use Revised July-2017