Rockwell Automation Safety Guidelines for the Application, Installation, and Maintenance of Solid-State Control - Manual (Page 19)

Publication SGI-1.1 - August 2009
Section 4: Installation Guidelines 19
Section 4: Installation Guidelines
4.1 Installation and Wiring
Practice 4.1.1
Proper installation and field wiring practices are of prime importance to the
application of solid-state controls. Proper wiring practice will minimize the
influence of electrical noise, which may cause malfunction of equipment.
User and installers should familiarize themselves with the follow installation
and wiring instructions in addition to requirements of all applicable codes,
laws, and standards. The manufacturer of the device or component in question
should be consulted whenever conditions arise that are not covered by the
manufacturer's instructions.
4.1.2
Electrical noise is a very important consideration in any installation of
solid-state control. While wiring practices may vary from situation to situation,
the following are basic to minimizing electrical noise:
1. Sufficient physical separation should be maintained between electrical
noise sources and sensitive equipment to assure that the noise will not
cause malfunctioning or unintended actuation of the control.
2. Physical separation should be maintained between sensitive signal wires
and electrical power and control conductors. This separation can be
accomplished by conduits, wiring trays, or as otherwise recommended
by the manufacturer.
3. Twisted-pair wiring should be used in critical signal circuits and noise
producing circuits to minimize magnetic interference.
4. Shielded wire should be used to reduce the magnitude of the noise
coupled into the low level circuit by electrostatic or magnetic coupling.
5. Provisions of the 1984 National Electrical Code
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with respect to
grounding should be followed. Additional grounding precautions may
be required to minimize electrical noise. These precautions generally
deal with ground loop currents arising from multiple ground paths. The
manufacturer's recommendations should be followed.
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Available from National Fire Protection Association, Batterymarch Park, Quincy, MA 02269
Comments: 4.1.2
A great deal of effort goes into the design of solid-state equipment to
achieve a reasonable degree of noise immunity. Filters, shielding, and
circuit design are all used. It is, however, impossible to design equipment
which is impervious to every form of noise found in the industrial setting.