MAN0974-11-EN_XL7_UserManual
March 22
nd
, 2020
Page 23 | 195
CHAPTER 4: ELECTRICAL INSTALLATION
NOTE: The datasheets are the first documents to refer to for model-specific information
related to XL7 OCS models such as pin-outs, jumper settings, and other key installation
information. Visit the Horner websites to obtain datasheets, user documentation, and updates.
North America
Europe
http://www.hornerautomation.eu
4.1
Grounding Definition
Ground: The term ground is defined as a conductive connection between a circuit or piece of
equipment and the earth. Grounds are fundamentally used to protect an application from harmful
interference causing either physical damage such as by lightning or voltage transients or from
circuit disruption often caused by radio frequency interference (RFI). Grounding is also for the
safety of the user.
4.2 Ground Specifications
Ideally, a ground resistance measurement from equipment to earth ground is 0
Ω
. In reality, it
typically is higher. The U.S. National Electrical Code (NEC) states the resistance to ground shall
not exceed 25
Ω
. Horner APG recommends less than 15
Ω
resistance from our equipment to
ground. Resistance greater than 25
Ω
can cause undesirable or harmful interference to the
device.