Emerson Process Management ControlWave EFM 3808 - Manual (Page 268)

Section 2 - Protection Page 2-3 S1400CW
Table 2-2 - Equipment Protection Site Safety Evaluation Guide (Continued)
# Guide Reference Section
6 Is there an antenna in the immediate area? See Section 4.1.2
7 How close is other equipment? Can someone safely touch this
equipment and a ControlWave simultaneously? See Section 2.3
8 Determine equipment ground requirements. How will the
ControlWave and its related wiring be grounded? Consider Earth
Ground, Circuit Ground, Conduit Ground, Site Grounds! See Section 3
9 Are there any obviously faulty or questionable power or ground
circuits? See Section 2.3
2.3 OTHER SITE SAFETY CONSIDERATIONS
Overhead or underground power or communication cables must be identified prior to
installing a new unit. Accidentally cutting, shorting or simply just contacting power,
ground, communication or process control I/O wiring can have potentially devastating
effects on site equipment, the process system and or personnel.
Don’t assume that it is safe to touch adjacent equipment, machinery, pipes, cabinets or even
the earth itself. Adjacent equipment may not have been properly wired or grounded, may be
defective or may have one or more loose system grounds. Measure between the case of a
questionable piece of equipment and its earth ground for voltage. If a voltage is present,
something is wrong.
AC powered equipment with a conductive case should have the case grounded. If you don’t
see a chassis ground wire, don’t assume that it is safe to touch this equipment. If you notice
that equipment has been grounded to pipes, conduit, structural steel, etc., you should be
leery. Note: AWWA’s policy on grounding of electric circuits on water pipes states,
“The American Water Works Association (AWWA) opposes the grounding of
electrical systems to pipe systems conveying water to the customer’s premises….”
Be sure that the voltage between any two points in the instrument system is less than the
stand-off voltage. Exceeding the stand-off voltage will cause damage to the instrument and
will cause the instrument to fail.