
MANUAL MOTOR STARTER GUIDE
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7.1.6 Selecting the right Short Circuit Current Ratings (SCCR) level for your UL application
With so many different applications and ratings available for manual motor starters, it can sometimes be difficult to
know which SCCR to select. Below is some general advice to assist in the selection. Additionally, an “SCCR reference”
is shown next to each application diagram in the previous section. This reference correlates to a UL/CSA maximum
short-circuit current rating table column header. These tables can be found in our Main Catalog for Motor Protection
and Control which can be accessed in the Download Center
All Categories > Prod-
ucts > Low Voltage Products and Systems > Control Product > Manual Motor Starters.
Figure 34: Screenshot from the catalog of the UL/CSA maximum short-circuit current rating table.
If the secondary winding style of the upstream facility transformer is known to be wye, or for delta networks
347 V AC and below, consider first the application of manual motor starters as combination motor controllers. For
manual control, select from the “Type E” SCCR. For remote control, select from “Type F”, and ensure that any mini-
mum component size requirements are respected.
For delta networks above 347 V AC, consider the addition of an upstream fuse block and fuses. The manual motor
starter can serve as the main branch disconnect when marked “Suitable as Motor Disconnect” and positioned on the
load-side of the branch circuit protective device. The “Motor disconnect” SCCR should referenced. These ratings ap-
ply whether the upstream BCPD contains fuses or a circuit-breaker unless otherwise noted.
For panels designed to control multiple branch circuits, consider the possibility of a group installation. Most indus-
trial control panels are supplied by a circuit-breaker or set of fuses that could be sized based on the requirements for
group installation. In the U.S., when using manual motor starters in group installations for manual control, the “Tap
Conductor Protection” SCCR should be referenced. For Canada, or for the U.S. when also combining AF contactors for
remote control, select from the “Group installation” SCCR. A 3-phase accessory busbar is available to provide a com-
pact solution for group installation.
If the upstream protective device is too large to protect the group, or if any of the other requirements for group in-
stallation cannot be met, manual motor starters should be employed as non-combination starters. They can provide
manual control themselves or provide overload protection as part of a magnetic or solid-state starter assembly.
Close coupling adaptors are available for AF contactors and PSR softstarters to reduce installation time and panel
space. In these applications, the “Motor disconnect” SCCR is referenced. If an additional controller is used (e.g. con-
tactor), use the component-level short-circuit current ratings for these devices.