Page 256 - Electrician - TT (Volume 2)

ELECTRICIAN - CITS

The goal is to produce a panel that is logically arranged and easy to maintain for the life of control.
Basic wiring practices
1 Wire: Use all 600V 90 Deg. C rated wire. Use stranded wire. Note any exceptions so these can be added to
the drawings or design notes.
2 Wiring across a hinged door or panel: U loop, as long as possible, facing down anchored on each side of
the hinge with screws or bolts (no adhesive). Place sleeve or spiral wrap over the wires running over the hinge
between the anchor points.
3 Spacing between wired devices and wireway or other obstructions: 2″ minimum; 2 1/2 – 3″ preferred
for 120VAC and less. 4″ for 480 volts (enough to insert a closed fist between the device and the wire way or
obstruction.
4 Minimize the use of cable/wire ties if wire duct is used: They get cut off when troubleshooting and are
rarely replaced. A good wire management system should not require any wire ties. Make it a goal to use no
wire ties except temporarily while wiring.

5 Leaving Slack: Generally, leave only “hidden” slack. Leave service loops as the wires leave or enter the
device or terminal. Run wires in the wire way so they enter and run to the middle or far side of the wire way
or duct. Take all corners in a wiring duct as wide as possible. Run wires in horizontal and vertical lines. This
also adds further “slack” and improves the appearance. Avoid looping wires in the wire way unless the wire
way is designed for this.
6 General Wire Routing: Run wires in horizontal and vertical lines, no diagonal runs. “Train” the wire by
bending it to make neat vertical and horizontal lines. Delicate wire will require “training” by bending and
forming the bend gradually. Wire in wire duct should be run so they do not cross each other excessively. Wire
entering or leaving a wire duct should be brought to the front of the duct before entering/exiting where possible.
Leave service loops and run wires in the wire way so they enter and run to the middle or far side of the wire
way or duct and take all corners as wide as possible. Do not run wire over other devices, including the wire
way. Elevate the duct and go under the duct with wires if needed. Review needed exceptions.
7 Wiring Power and Motor Wiring: Place Pig tail loops between devices that are spaced such that it makes it
easier to remove wiring if the pig tail is added. Consider using High Flex power wires such as “Railroad Wire”
or high strand count wire. Train the wire by bending it in the direction you want it to go or lay in the duct, rather
than just trying to lay it in a wire duct and hope it “stays down” in the duct. See also “General Wire Routing”.
8 Wiring Signal and Shielded Cables: Use 18 AWG shielded, twisted pair (or Triad) type cables rated at 600V
as the default signal wire type. Unless specifically required strip off a generous amount of the jacket so that
each conductor can be easily accessed for removal, testing, and replacement. Also remove the jacket as it
exits a wire duct, keeping the twists where the cable otherwise creates unwanted wire congestion. Examples:
going to Analog I/O modules, or routing to elevated side terminals. Terminate all shields. Terminate all shields
close to the signal wires. Consider using 2, 3, or even 4 high terminal blocks with jumper slots for signal wiring
depending on the wiring needed. This allows busing the power supply voltages for a cleaner installation.
Option: Place heat shrink tubing 1/2 over the cut end of the cable jacket and 1/2 over the exposed wires.
9 Wiring Control Wires: Use 14 SWG 600V (stranded) wire for 120VAC wire. Use 16 or 18 SWG 600V(stranded)
wire for 24VDC wire for up to 10 and 5 amps respectively. Use “General Wire Routing” recommendations
found elsewhere in this document.
10 Terminations: leave some bare wire showing to allow visual inspection and to avoid screwing down on the
insulation. Wires should exit the terminal straight. Do not bend the wire at the point of termination. Instead
loop or bend wires on the insulation that do not go straight to the wire way.
11 Terminals: Screw terminals:Use tubular, pressure plate type screw terminals that minimize wire distortions or
damage when terminating. Position Terminals to allow visual inspection of the recessed connections. Elevate
Control Terminals to allow wiring under the terminals if needed. Keep it stiff using a heavy-duty DIN rail or
Hoffman Terminal Straps or equivalent. Angle and elevate terminals mounted on the side panel for wiring ease
and to allow visual inspection of wiring in the terminals.

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CITS : Power - Electrician & Wireman - Lesson 93-100