Grounding; Chassis Ground Lug - Emerson FB3000 Instruction Manual

2.5

Grounding

There are four separate and distinct ground references within the FB3000 architecture.
The chassis ground lug (also known as Protective Earth or PE), internal system bus
ground, isolated ground, and the 24V loop ground (for modules that support loop power).
2.5.1

Chassis Ground Lug

The RTU includes a chassis ground lug to the left of the power supply modules. In CSA
documents, this may be called the Protective earthing (PE) conductor. The chassis ground
lug provides a path to earth ground for electrical safety, static discharge, and stray
voltage from a lightning strike.
DANGER TO PERSONNEL AND EQUIPMENT
Do not use the chassis ground lug for a direct connection to a lightning
arrestor/lightning rod.
The chassis ground lug is completely isolated from the isolated, signal, and loop power
ground terminals on I/O modules, or from the 24V loop power ground terminal on some
I/O modules. To prevent noise and equipment damage, you should keep these grounds
separate from the chassis ground.
Figure 2-5. Chassis Ground Lug Location (8-slot left, 4-slot right)
Once you have installed the unit, run a ground wire (14 AWG protective conductor)
between the chassis ground lug and a known good earth ground.
Use stranded copper wire to earth ground and keep the length as short as possible.
Clamp or braze the ground wire to the ground bed conductor (typically a stranded copper
AWG 0000 cable installed vertically or horizontally).
Installation
CAUTION
FB3000 RTU Instruction Manual
D301851X012
November 2023
15