Load And Control Wiring - Siemens tiastar Instruction Manual

3.15 Load and control wiring

All interconnections between devices within each
control unit are prewired at the factory. Field wiring
to each control unit should be made in accordance
with the wiring diagram indicated on the lead sheet
for that particular unit. The lead sheet and wiring
diagrams are included in the information packet.
When wiring or performing any maintenance on
plug-in units, disengage the stabs by withdrawing
the unit. Refer to page 24, "Plug-In unit removal"
section. Wiring done with the unit in this position
will ensure adequate cable slack to allow unit
withdrawal to the same position when future
maintenance is required. Always use stranded wire.
The vertical wiring between control units or
between a control unit and conduit should be pulled
through the vertical wireway on the right side of
the frame. These wires should then be tied or laced
together and the resulting bundle then securely
fastened to the wire supports. Interconnecting
wiring between control units should be routed
through the top or bottom horizontal wireways.
Installation and wiring must be in accordance with
NFPA-70, ANSI, the National Electrical Code, and
any other applicable regional codes or regulations.
3.15.1 NEMA type A wiring
Motor control centers with NEMA type A wiring do
not include terminal blocks. All field wiring, both
power and control, should be connected directly
to the individual components.
3.15.2 NEMA type B wiring
Motor Control Centers with NEMA type B wiring
include terminal blocks for control circuit
connections.
NEMA type B user field load wiring for combination
motor control units size 3 or smaller shall be
designated as B-D or B-T, according to the following:
• B-D connects directly to the device terminals,
which are located immediately adjacent, and
readily accessible, to the vertical wireway.
• B-T connects directly to a load terminal block in,
or adjacent to, the unit.
3.15.3 NEMA type C wiring
Motor control centers equipped with NEMA type C
wiring include all the features described for NEMA
type B wiring in addition to master terminal blocks
located at either the top or bottom horizontal
wireway. (Figure 46) Motor control center units are
factory wired to their master terminal blocks.
20 (508) Deep
15 (381)
Front
Deep
12
(305)
Terminal
block
Side View
location
(Front only
structures)
Type C Terminal Blocks: Standard Location in Top Horizontal Wireway
dimensions shown in inches (mm)
Figure 45: Master terminal block location
The motor control center lead sheet, located in the
information packet, indicates the type of wiring
provided for this installation.
Figure 46: Type "C" wiring terminal
Field terminations: NEMA classes and types
Description
Terminals furnished
• For all control connections
• For starter load connections
Terminals mounted
• On control unit
• In master terminal compartment
Interwiring
• Between units in the same motor control center
tiastar™ Motor Control Centers Instruction Manual Installation
20 (508) Deep
15 (381)
Deep
6 (153)
Side View
Front
Restricted to one
row terminals
Class I types
A B-D B-T C
X X X
X X
X X X
X
Class II types
B-D B-T C
X X X
X X
X X X
X
X X X
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