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ROC827 Instruction Manual
Issued Mar-06 Installation and Use 2-4
2.1.4 Power Installation Requirements
Be sure to route power away from hazardous areas, as well as sensitive
monitoring and radio equipment. Local and company codes generally
provide guidelines for installations. Adhere rigorously to all local and
National Electrical Code (NEC) requirements.
The removable terminal blocks accept 12 American Wire Gauge (AWG)
or smaller wiring.
Although the ROC827 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 ROC827 does not power. Similarly, when
the ROC827 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.
2.1.5 Grounding Installation Requirements
If your company has no specific grounding requirements, install the
ROC827 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 ROC827 EIA-232 (RS-
232) port, ground the ROC827 Power Input module either by connecting
the PM-12’s BAT– to ground or by connecting either of the PM-24’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 ROC827 helps to reduce the effects of electrical noise on
the ROC827’s operation and protects against lightning.